This cake isn’t just chocolate—it’s a full-on candy bar experience baked into a pan. With its rich, moist base and a creamy, mousse-like filling that captures the essence of a Three Musketeers bar, this dessert is pure indulgence. The texture contrast between the fluffy cake, smooth filling, and light whipped topping makes every bite heavenly.
While the recipe has a few steps, it’s surprisingly simple to follow—and totally worth it when you slice into that creamy center. If you manage to have any leftovers, stash them in the fridge (though chances are, they’ll disappear fast).
Ingredients For Decadent Chocolate Mousse Layer Cake
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1 box devil’s food cake mix (e.g. Duncan Hines)
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3 large eggs
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1/3 cup canola or vegetable oil (80 mL)
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1 cup water (240 mL)
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3 boxes instant chocolate pudding (3.9 oz / 110 g each, Jell-O brand)
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2 tubs Cool Whip (8 oz / 226 g each)
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1 package cream cheese, softened (8 oz / 226 g)
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1 1/2 cups 2% milk (360 mL)
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1 teaspoon pure vanilla extract (5 mL)
How To Make Decadent Chocolate Mousse Layer Cake
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Preheat your oven to 325°F (160°C) for coated or dark pans, or 350°F (175°C) for glass or light metal pans. Lightly grease a 9×13 inch (23×33 cm) pan with butter or spray, then dust with flour. Shake out the excess flour and set the pan aside.
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Prepare the cake batter by mixing the boxed cake mix with the eggs, water, and oil. Once well blended, mix in 1 box of chocolate pudding powder and stir until smooth. Pour into the prepared pan and bake for 26–29 minutes, or according to box directions.
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While the cake is baking, prepare the filling. In a bowl, beat the softened cream cheese with 1/2 cup (120 mL) of milk and the vanilla until smooth. Add 1 box of chocolate pudding mix and another 1/2 cup (120 mL) of milk. Blend well.
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Fold in one entire tub of Cool Whip into the chocolate mixture. Refrigerate until the cake is ready to be filled.
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After the cake has fully cooled, gently slide a frosting spatula around the edges of the pan to loosen the cake. Place a cookie sheet over the top of the pan, hold both together, and flip quickly. Tap the bottom of the pan to release the cake. Once released, use a serrated knife to carefully cut the cake horizontally into two even layers.
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Place the bottom layer back into the pan or onto a tray. Remove the filling from the refrigerator and give it a few stirs to soften. Spread the mousse filling evenly over the bottom layer.
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Carefully place the top layer of the cake back over the filling, aligning it with the bottom.
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In a new bowl, blend the final 1/2 cup (120 mL) of milk with the remaining box of pudding mix. Once thickened, fold in the second tub of Cool Whip and mix well.
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Spread this creamy topping over the top of the cake as frosting. It’s now ready to serve!
Bonus Tip: For a softer, creamier top layer, prepare the pudding with the full amount of milk as instructed on the box, then blend in the Cool Whip before spreading it onto the cake.
Final Thoughts
This layered mousse cake takes everything you love about a candy bar and turns it into a show-stopping dessert. The contrast of fluffy cake, rich filling, and light topping makes it perfect for birthdays, holidays, or just because you’re craving chocolate. It’s nostalgic, comforting, and a guaranteed crowd-pleaser.
Let the compliments roll in—and don’t forget to grab a fork before it’s all gone.
