Chocolate Royal Cake, also called Trianon, calls for chocolate lovers. Some cakes are more traditional than others, and this is one of them: a chocolate mousse cake with a crunchy layer over an almond biscuit base (=dacquoise).

Chocolate Royal Cake is a classic French dessert in its pure elegance you will find in every bakery when visiting France. The combination of the chocolate mousse and the crunchy layer brings an amazing texture that you won’t resist.
This Chocolate Royal Cake is not too complicated to make. Each layer is very approachable, and I keep things easy by dusting the top with cocoa powder and skipping the chocolate mirror glaze you sometimes see on this mousse cake.

Note:
If you have a passion for French pastries, you will be interested to know that this Chocolate Royal Cake is also called a Trianon Cake (2 names but the exact same cake). The traditional cake has a crunchy layer made of Paillete Feuilletine (= lacy crepes), but it can be hard to find in grocery stores, so I replaced it with cornflakes, and the result is amazing.
Why you’ll love this Chocolate Royal Cake
- Flavorful: the chocolate mousse pairs perfectly with the crispy layer (made with hazelnut praline paste) and the almond dacquoise (=biscuit base).
- The texture is fantastic: the melt-in-your-mouth chocolate mousse and crispy layer combine perfectly in every bite.
- A classic French cake you can easily make in your home kitchen, just like the Triple Chocolate Mousse Cake (another French classic).
- This chocolate dessert is perfect for chocolate lovers or to serve on special occasions like birthdays, Christmas and Easter.
Equipment Needed
- Cake ring 20cm / 8in – minimum height: 8cm / 3in
- Cake collar, also called acetate sheet.
- A cooking thermometer, it’s not compulsory but can help you get more precise results to make the chocolate mousse.
- And classic baking stuff like baking paper, spatula, etc….

Ingredients
Dacquoise (biscuit base): almond meal (or ground almond that you sieve), egg white from large eggs (keep the yolk for the chocolate mousse), powdered sugar, and fine sugar (caster or granulated sugar)
Crunchy layer: milk chocolate (40%), cornflakes, hazelnut praline paste (homemade or store-bought)
Chocolate mousse: egg yolk (from large eggs), whole milk, heavy cream (36% milk fat), chocolate with 52% cocoa content (you can choose a 60% cocoa content if you love dark chocolate.)
How to make a Chocolate Royal Cake / Trianon?
Here is a summary of the recipe. Get all measurements, ingredients, and instructions at the end of this post.
Step 1: dacquoise (The dacquoise is a biscuit base made from a French meringue, combined with almond meal. It is crispy on the outside but still moist and chewy in the center.)
- Prepare the batter.
- Spread the batter in a circular pattern on a baking sheet.
- Bake until lightly golden and no longer sticky to the touch.
- Let it cool completely before handling it.
- Then, cut it to fit inside your cake ring and place it in the cake ring with cake collars (=acetate sheet).
Step 2: Crunchy Layer
- Melt chocolate and add hazelnut praline paste. Mix.
- Stir in cornflakes, previously crushed, until fully coated.
- Spread the crunchy mixture on top of the dacquoise and place in the fridge until it is set (20-30 min).
Step 3: Chocolate Mousse
- Prepare the chocolate mousse by combining a custard cream with chocolate, then folding it in whipped cream. Pour the mousse over the crispy layer and spread evenly.
- Chill for 6 hours or overnight.
Step 4: Decoration
- Decorate the cake with cocoa powder 10-15 minutes before you plan to serve it. If you do it too early, the cocoa powder will absorb moisture.
- Decorate with chocolate decor.


Tips
Chocolate mousse:
- When making the custard, constantly whisk to avoid a lumpy cream.
- When ready to add to the whipped cream, the chocolate cream needs to be around 40C (105F). That’s very important. If it is too cold, you will have difficulties folding in the whipped cream. On the other hand, if the chocolate cream is too hot, the whipped cream will lose its airy texture and flatten out.
Cake:
For a professional look, use a cake collar, the side of the mousse cake will be smooth, and it will be so much easier to remove the cake ring.
Decoration:
As said previously, decorate the cake with cocoa powder 10-15 minutes before you plan to serve it. If you do it too early, the cocoa powder will absorb moisture.
Variation
The dacquoise: You can use hazelnut meal instead of almond meal for a full hazelnut version, or make half almond/hazelnut.
Decoration: replace the chocolate decor with hazelnuts or chocolate curls.
FAQs
How to store the Chocolate Royal Cake?
Store this cake for 2-3 days in the fridge under a cake dome.
Can I make it ahead?
If you make the hazelnut praline paste, you can prepare it ahead of time. It stores very well for a few weeks.
For the cake itself, it is best to prepare the cake the day before you plan to serve it. It will need about 6 hours to set.
I won’t recommend freezing this cake due to the ingredients.

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