Name: How to make a Fraisier with Mousseline Cream
Prep time: 45 min
Cook time: 25 min
Total time: 1 h 10 min
Ingredients: 2 large eggs (about 100 g, 3.5 oz.), at room temperature; 60 g granulated sugar (2.1 oz.); 60 g all-purpose flour (2.1 oz.); 65 g strawberries (fresh or frozen) (2.3 oz.); 35 ml water (1.2 fl oz.); 30 g granulated sugar (or to taste) (1 oz.); 300 g (293 ml, 9.9 fl oz.) whole milk; 3 large egg yolks (about 55 g, 1.9 oz.), at room temperature; 75 g granulated sugar (2.6 oz.); 16 g cornstarch (0.6 oz.); 12 g all-purpose flour (0.4 oz.); 40 g unsalted butter cut into cubes, cold (1.4 oz.); 1 teaspoon vanilla extract; 90 g unsalted butter, cut into cubes and slightly softened (see notes) (3.2 oz.); 150 g fresh strawberries (or as needed) (5.3 oz.)

Fraisier Make-Ahead Tips

Let’s talk a little bit about the four basic components of a fraiser and see how to split the tasks to fit our busy schedule!

Genoise

We saw last time how to make genoise. You’ll need about 25 minutes to prepare and bake the genoise. But you will have to wait for it to cool down completely before assembling the fraisier. You could prepare it in the morning but I personally like to prepare it the night before. Once it has cooled down, wrap it tightly (in plastic wrap if you’d like) and store it at room temperature (up to a day) or in the refrigerator (up to 3 days). A chilled genoise will be even easier to slice.

Syrup

The syrup can be made several weeks in advance and stored in the refrigerator. You can make a simple syrup to brush over the genoise if you’d like. To make the syrup, simply bring equal amounts of sugar and water to a boil, stirring occasionally to dissolve the sugar.

But for this recipe, I chose to make a strawberry syrup, to give the fraisier even more of a fruity flavor. The only difference is that you pour the cooled syrup over pureed strawberries and you get a delicious strawberry syrup. For a deeper strawberry flavor and color, it’s best not to heat the strawberries. But if you are like me and you forget to thaw the strawberries, you can take a shortcut and heat the strawberries with the syrup! It will still taste great.

Mousseline cream

Mousseline cream is obtained by adding softened butter (or sometimes butter cream) to pastry cream, and whipping until silky smooth and glossy. The added fat will firm up when chilled and will make the cream more pipeable than pastry cream. This cream is often used as a substitute for French buttercream as it is lighter.

The amount of sugar used in mousseline cream is higher than it would be for pastry cream, to balance out the large quantity of butter added. The added sugar could however cause the cream to scorch easily so it is best to cook it at a lower temperature than regular pastry cream.

We will see how to make mousseline cream in the next section with step-by-step pictures.

Fresh strawberries

It’s best to wash and hull the strawberries ahead of time so that they are properly dry before using them in the cake.

You will need fresh strawberries for:

The edges of the cake: You’ll need strawberries that are approximately the same size. We’ll cut those in two, lengthwise.
The inside of the cake: You can add as many strawberries as you’d like inside the cake. I usually dice them as I find it easier to cut (and eat!) the cake this way. But you could slice them in two or even use whole strawberries, although you might have a bit of trouble cutting the cake.
The decoration: You can also decorate the top of the cake with strawberries if you’d like.

close up shot showing inside layers of a fraisier cake.

Making Mousseline Cream, Step-by-Step

The first thing we have to do is prepare the pastry cream. In case you missed it, we previously covered in depth how to make pastry cream and we went over some troubleshooting tips.

Preparing the pastry cream

In a small pot, heat the milk and part of the sugar (about 1/3) until simmering.
In the meantime, whisk the egg yolks and sugar together in a bowl. Whisk as soon as you add the sugar to the egg yolks or you will “cook” the eggs.

egg yolks and sugar in small white bowl.

Sift the flour and cornstarch over the egg mixture and mix to combine.
Temper the eggs: Slowly add part (about half) of the hot milk to the egg mixture and keep whisking. Pour as much milk as necessary until the egg mixture becomes thin enough for you to pour it back into the pot easily.

egg yolk- sugar mixture in small white bowl.

sifting cornstarch and flour through a fine mesh sieve over egg yolk mixture

pouring hot milk over egg yolk mixture to make mousseline cream

Return the mixture to the pot and cook on medium heat, whisking constantly. Once the foam subsides and the cream starts to thicken, keep an eye out for bubbles forming. When this happens, keep heating for another 2 minutes. This will ensure you get rid of any starchiness and inactivate the enzyme (amylase) that could make your pastry cream runny after a while. Remove from the heat. Don’t whisk too much when the cream starts boiling. Whisk just enough for it not to stick to the bottom of the pot. Optional: If you notice any lumps in your cream, strain your cream through a fine-mesh sieve into a bowl.
Add the cold butter and vanilla extract and whisk until the cream is completely smooth.

checking temperature of pastry cream by inserting a digital thermometer into the cream.

Cooling the pastry cream

Pour the cream into a large container to obtain a thin layer. This will ensure the cream cools down quickly.
Place a piece of parchment paper or cling film straight onto the surface of the cream to prevent a skin from forming. Refrigerate for as long as needed until the temperature of the cream is around 16°C (60°F). The thinner the layer of pastry cream, the faster it will cool down. My layer wasn’t too thin and it took about 1 1/2 hours to get to the right temperature. Some bakers freeze the pastry cream for 15 minutes to speed up the process.

hot pastry cream poured into glass container.

parchment paper placed on surface of pastry cream to prevent a crust from forming.

fraisier decorated with marzipan and sliced strawberries.

Adding butter to the pastry cream to make mousseline cream

The pastry cream shouldn’t be refrigerated for too long before mixing in the softened butter. The large temperature difference would cause the butter to firm up again, leaving you with a lumpy cream. You should refrigerate the cream just until it is slightly cool. Ideally, you want both the pastry cream and softened butter to be at a temperature of around 16°C (60°F). If your pastry cream is too cold, let it warm up at room temperature a little before adding the butter.

Before the pastry cream gets to the right temperature, take the butter out of the fridge and cut it into pieces. Let it warm up to 16°C (60°F).
In the bowl of a stand-mixer fitted with the whisk attachment, whip the pastry cream on medium speed to loosen it, about 2 minutes.
Gradually add the butter and keep whipping on medium speed until the cream is silky smooth and glossy, about 10 minutes. Don’t stop mixing as soon as the ingredients are combined. Keep mixing a bit longer to incorporate more air. The cream should hold its shape.
Transfer to a piping bag fitted with a large plain tip. If you aren’t planning on using it immediately, you can refrigerate the cream in the piping bag.

checking temperature of pastry cream using a digital thermometer.

pastry cream whipped in stand mixer bowl to loosen it.

adding butter pieces to pastry cream to make mousseline cream.

silky mousseline cream in stand mixer bowl.

Troubleshooting Mousseline Cream

The two most common issues encountered when making mousseline cream are lumpy texture or runny consistency.

The cream has butter lumps in it

This is due to a temperature difference between the pastry cream and the butter. If you add cold butter to warm pastry cream, or warm butter to cold pastry cream, you’ll have trouble getting a smooth cream. Solution: Keep whipping the cream until it becomes smooth. The cream will eventually warm up from the mixing and it will be easier to combine the two components. You could also place the mixing bowl in a bowl of hot water for a few seconds to gently warm it up, before whipping again. Repeat as needed.

The mousseline cream is runny

Too hot: Adding hot pastry cream to the softened butter would melt the butter, resulting in a runny cream. Be sure to cool down the pastry cream before using it. And try to have both the pastry cream and butter at the same temperature. Mixing at high speed would also cause the butter to melt so mix on medium speed. Solution: Refrigerate the cream for a few hours and try whipping it again.
Underwhipped: When you add the softened butter to the pastry cream, don’t stop mixing as soon as they are combined. You need to incorporate air so keep mixing for about 10 minutes.
Pastry cream undercooked or overmixed: When transferring the cold pastry cream to the mixing bowl, it should release very easily and fall in one block. If it’s too creamy (and you are sure it’s cold enough), you probably needed to cook it longer or you whisked it too much. For more details, check out the troubleshooting section in the pastry cream post (section 8). Solution: When cooking the pastry cream, keep heating it for 2 more minutes when you notice the first bubbles forming. When the cream is boiling, don’t whisk it continuously but just enough for it not to stick to the pot.

Assembling The Fraisier

You’ve made the genoise and syrup and they have cooled down. Your mousseline cream is ready to be piped. Time to assemble the fraisier!

Preparing the strawberries

Select strawberries of similar height to use for the edges of the cake. Slice them in half, lengthwise. I used about 8 strawberries for a 16 cm/ 6 1/3 inch cake ring.
Dice a few strawberries to fill the cake. You might not need all the strawberries so I personally find it better to dice only a handful in the beginning. You can always dice some more later.

close up shot of a slice of fraisier on a plate.

First layer of the fraisier

Using a cake ring is ideal because you can place it over your serving platter right away. I use an extendable cake ring so I don’t have to buy several sizes and it’s proved quite handy. But if you don’t have one, you could use a springform pan.

Cut a strip of parchment paper slightly taller than your cake ring (or pan) and long enough to line the sides of the ring. This will make it easier to unmold the cake. Place the strip inside the pan and use paper clips (or pegs), if desired, to hold the paper in place until you start filling the cake. You can use a rhodoid strip instead of parchment paper if available.
Slice the genoise horizontally in two using a serrated knife or a cake leveler.
Place the strawberry halves vertically inside the cake ring as tightly as possible, cut side against the parchment paper.

strawberry syrup for fraisier in small white bowl.

genoise for fraisier sliced in two using cake leveller

sliced strawberries arranged all around edges of cake ring to make fraisier.

Place the genoise half, cut side up, at the bottom of the pan. You might need to cut it a little around the edges so that it fits within the borders created by the strawberries.
Generously brush the genoise with strawberry syrup.
Cover the genoise with chopped strawberries.

genoise placed at bottom of cake ring, within borders created by strawberries to make fraisier.

genoise brushed with strawberry syrup to make fraisier.

chopped strawberries placed over genoise to make fraisier.

Pipe mousseline cream between the vertical strawberries. I like to push the strawberry against the pan when piping to make sure I don’t end up covering with cream the side that will be visible when unmolding. Then proceed to piping mousseline cream all over the chopped strawberries in a spiral movement.
Using a spoon, spread the cream a little, if needed, to make sure you have an even layer.

mousseline cream piped between strawberries to make fraisier.

mousseline cream spread with a spoon for an even layer in fraisier.

Second layer of the fraisier

Place the second genoise, cut side up, over the cream. Gently press down so that the cream goes up the sides. You might need to cut the edges of the genoise a little so that it fits.
Cover with chopped strawberries then pipe the cream and smoothen with a spatula.
Refrigerate for at least 3 hours.

pressing second genoise layer into mousseline cream to make fraisier.

mousseline cream piped on top of chopped strawberries to make fraisier.

Serving The Fraisier

Before serving the cake, remove the cake ring (or the sides of the springform pan). Then gently remove the parchment paper (or rhodoid strip). Decorate as desired. I covered my fraiser with homemade marzipan (tinted with a few drops of red food coloring) and decorated with a few strawberries. If you’d like to cover the fraisier completely with strawberries, you could layer the strawberries as I have done with the strawberry tart.

And that’s it! If you are intimidated by this cake like I was, I hope the step-by-step pictures will give you the motivation needed to make it!