This triple chocolate mousse tart is the ultimate tart. It’s rich but subtle, sweet but lightly salty, and it has the most amazing texture combination of smooth, silky, and soft but crunchy. This tart is so good that you will want to pass the recipe on for generations!
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What is a Triple Chocolate Mousse Tart?
A triple chocolate mousse tart is a combination of a chocolate crust, dark chocolate mousse, and white chocolate mousse layered into one beautiful dessert.
For the crust, we use a chocolate sable cookie that is formed into the tart pan and then baked to perfection. It’s not too soft and not too firm, and it’s just slightly salty to balance out the sweetness of the mousse.
The dark chocolate mousse is silky and rich, but the white chocolate mousse is light and balances out the flavor of the entire tart. This recipe was inspiring by America’s Test Kitchen’s chocolate mousse cake.
What is the Best Chocolate for This Tart?
- For the crust, it just calls for 2 ounces of chocolate. But using 60% bittersweet chocolate makes the crust less sweet than if we use semi-sweet chocolate. As with most crusts, it should be more on the lightly salty/less sweet side.
- For the dark chocolate mousse, we use the same 60% bittersweet chocolate baking bar (Ghiradelli is the BEST chocolate for this recipe). You can find this chocolate at most grocery stores now too, so it won’t require a special trip to a fancy chocolate store.
- For the white chocolate mousse, use good quality white chocolate chips. Either Ghiradelli or Guittard work well.
- The quality of the chocolate is so important when making this triple chocolate mousse tart. It is such a special dessert that you should definitely not skimp on using quality ingredients.
How Do You Make a Good Triple Chocolate Mousse Tart?
- Make the crust and press it into the tart pan with the back of a measuring cup so that the crust is really thin and even.
- Dock the crust and refrigerate it for 30 minutes so the crust is firm before baking.
- Line the crust with foil and pie weights and bake.
- To make the second layer of the tart, melt the chocolate and stir together with cocoa powder and hot water.
- Whip heavy cream, sugar and salt to soft peaks
- Fold chocolate into whipped cream and pour into cooled crust. Smooth out chocolate mousse and refrigerate for 20 minutes.
- To make the top layer, heat 1/4 cup heavy cream on stove and stir in bloomed gelatin.
- Pour heavy cream over white chocolate chips and stir to melt.
- Whip remaining heavy cream and sugar to soft peaks and fold into chocolate.
- Pour over dark chocolate mousse and spread evenly. Refrigerate for at least 2 hours so the mousse has time to set up properly.
What do I Need to Make This Tart?
- A good 9-inch tart pan with a removable bottom is essential. Why do they even make tart pans without a removable bottom? It is so much easier to remove a tart from the pan to cut and serve it!
- Pie weights help to keep the crust from shrinking during baking, so make sure you use pie weights or rice in the foil liner.
- An offset spatula to smooth out the the layers of chocolate mousse.
- These amazing cutting boards for chopping the chocolate.
- 5 Tbs unsalted butter, softened
- 1/4 cup light brown sugar
- 1/2 tsp vanilla
- 2 ounces semi-sweet chocolate bar or 60% dark chocolate bar, chopped into small pieces
- 1/2 cup all-purpose flour
- 1 Tbs unsweetened cocoa powder (1 oz)
- 1/2 tsp Fleur de Sel or flaked sea salt
- 3 tsp cocoa powder(Dutch-processed)
- 2.5 Tbs water
- 3 oz. baking chocolate bar, 60% cocoa(bittersweet)
- 2/3 cup heavy cream
- 2 tsp sugar
- pinch salt
- 1/4 + 1/8 tsp gelatin
- 1/2 Tbs cold water
- 3 ounces white chocolate chips
- 3/4 cup heavy cream
- 1/2 tsp sugar
For the Crust
- Preheat oven to 350 degrees. Cream butter, brown sugar, and vanilla until smooth.
- Chop chocolate into thin slices, almost like shaved chocolate pieces.
- Add all dry ingredients to the mixer and mix just until combined.
- Pour dough into a 9-inch tart pan and press dough evenly into pan with the back of a measuring cup. Be sure to press dough firmly against the sides and trim off excess dough. If the crust is thin enough, you should have removed enough chocolate cookie dough to make 2 or 3 cookies afterward.
- Dock tart(prick with a fork), line with nonstick foil, and fill with baking weights. Refrigerate for 30 minutes, and then bake for 15 minutes.
- After 15 minutes, remove tart from oven, carefully remove foil, and bake for 5 more minutes.
- Remove tart from oven and let cool completely, about 45 minutes.
For the Middle Layer
- Combine hot water and cocoa powder in a bowl and set aside.
- Melt chocolate in a double boiler and remove from heat. Stir in hot water/cocoa powder and set aside.
- In a stand mixer or with a hand mixer, mix heavy cream, sugar, and salt until soft peaks form.
- Stir 1/4 of the whipped cream into the chocolate, and then fold the remaining whipped cream in until no streaks show.
- Pour mousse into tart shell and spread evenly with an offset spatula. Refrigerate for 20 minutes and prepare top layer.
For the Top Layer
- Pour water into a small bowl and sprinkle gelatin over the water. Let gelatin bloom for 5 minutes.
- Bring 1/4 cup of heavy cream to a boil and stir in gelatin.
- Put chocolate chips into a bowl and pour heavy cream mixture over the chocolate chips. Stir until melted. Let cool for 8-10 minutes, stirring occasionally.
- Whip the remaining heavy cream and sugar until soft peaks form.
- Stir 1/4 cup of whipped cream into chocolate and then fold the remaining whipped cream into the white chocolate.
- Pour white chocolate mousse into the tart and spread evenly. Refrigerate for at least 2 hours and enjoy. Keep leftover tart slices refrigerated.
- If desired, double the white chocolate mousse recipe to make a white chocolate star border as shown in the pictures. Otherwise, top with shaved chocolate or cocoa powder.
This is a Baker Street Society recipe.
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