Decadent Chocolate Mousse Cake (No Gelatin!)

This chocolate mousse cake combines a dense layer of chocolate fudge cake topped with a light and airy layer of chocolate mousse. Made without gelatin, the lightness of the mousse is made from a combination of whipped egg whites and heavy cream. To top it off, add a bunch of berries for a decadent and elevated chocolate dessert that is actually really easy to make!

If my 5 star rated flourless chocolate cake and my cosmic brownies had a baby, it would be this chocolate mousse cake. With its rich, fudgy, and dense bottom layer, under a light, airy, whipped chocolate topping, this cake has the perfect balance of textures.

When testing this cake I wanted to make sure that the mousse layer was just as high, if not higher than the fudge bottom, and I also wanted it to be gelatin free. Even as a trained pastry chef, gelatin just isnt something I use in my house, and I dont think its a common ingredient in other homes, so I set off to test this without it!

Instead of using gelatin for stability, the mousse layer gets it’s airiness from whipped egg whites and whipped heavy cream. I first tested out using only egg whites but found it wasnt enough. The addition of whipped cream gives the mousse extra height and stability.

The best part is it’s easy to make at home from scratch! The ingredients are simple, and the process is straightforward. The only thing thats a little out of the ordinary is having to get a strip of acetate for lining the springform pan. See below for my notes on that!

While tasting this recipe, I heard one of my friends say, “This is like something out of a fancy restaurant!” 

Wohoo!

Ingredients and Equipment

Let’s highlight a few of the important ingredients and equipment you’ll need to make this cake look and feel like it came right out of a professional bakery! 

Acetate Cake Collar: Acetate, or a “cake collar”, is a thin strip of plastic that wraps around cakes. You use it to keep pourable things like mousse, or curd from spilling out over a cake until it has chilled and solidified over the cake.

It comes in a roll so you can cut it to any shape you want. Plus you can re use it! I use the same one for this recipe all the time. All you have to do is line it in the cake pan, pour in your mousse, then when it is chilled, pull it off!

70% Dark Chocolate: Choosing 70% dark chocolate for this recipe is ideal because it offers a perfect mix of flavor and texture. It has a rich, deep taste that isnt too sweet. It also melts beautifully, contributing to the smooth and creamy texture of the mousse.

Rubber Spatula: Using a spatula to fold egg whites into the chocolate mixture is key for a few good reasons.

• The spatula is gentle and helps keep the light, airy structure of the whipped egg whites intact. This is important for getting that fluffy texture in the mousse. If you mix too hard with something like a whisk, you’ll lose all those air bubbles in the egg whites, making the cake heavier.
• The spatula also helps mix everything evenly without overdoing it. By using a spatula, you’re helping to make sure your cake turns out light and airy, just as it should be.

Glass bowl: I like to use a glass bowl for this recipe because as you are folding you can look on the bottom of the bowl to see if you missed any chocolate when folding in the egg whites.

Raw eggs

Yes this recipe uses raw eggs. It’s not something I am worried about especially with eggs being pasteurized. If it worries you, then make my baked flourless chocolate cake instead. It’s light and airy too and not dense at all!

If you dont have a spring form pan

Honestly, why not? LOL, I use it all the time for cheesecake recipes and one layer cakes! To use the acetate liner you’ll need a springform pan because it un-clicks and allows you to get the liner onto the edges of the cake.

If you dont have one then use a cake pan with high sides, you wont be able to use the acetate and you dont want the mousse spilling over.

No acetate?

If you dont want to get the cake collar, you can use parchment instead, its just not as sturdy.

How to make the cake

Prep for baking: Preheat the oven to 350° F and spray and line a 9-inch springform pan with baking spray and parchment paper.

Don’t skip the spray, it’ll help the cake release when you need to add the acetate liner. If you skip it, the cake may crack and stick to the sides.

Assemble the cake batter: Melt the chocolate and butter together in the microwave. Add the sugar, eggs, and vanilla, mixing at low speed with a hand mixer or by hand until combined. Mix in the flour, cocoa powder, and salt until just combined without overworking. 

Bake the cake layer: Pour the cake mixture into the prepared cake pan and bake for 25-28 minutes or until the center is set. Cool completely. 

Start the chocolate mousse: Melt the butter and chocolate in an 8-inch bowl. Add the instant coffee mixed with hot water. Separate the eggs by adding the whites into the mixing bowl of a stand or hand mixer and the yolks into the chocolate mixture. Mix the chocolate mixture with a spatula until combined.

Whip the egg whites: Using the whisk attachment whip the egg whites on high speed, pouring in the sugar slowly while whipping. Continue whipping until stiff peaks form. You know the whites are ready when you take the beater out, flip it upside down, and the tip of the egg white can hold itself up. Fold 1/3rd of the egg whites into the chocolate mixture at a time, making sure not to deflate them. Fold until there are no white streaks left, then continue until there are no more egg whites. 

Whip the heavy cream: Lightly clean out the bowl and whip. Pour the heavy cream and cream of tartar into the bowl. Whip on high speed for 1-2 minutes until there are stiff peaks. This can happen fast so make sure to watch it. Otherwise it can curdle! Fold into the mousse.

Assemble and chill: Unsnap the springform pan to release the cake. Line the acetate around the edges, making sure it touches the bottom of the pan. Make sure it’s at the bottom, or the mousse will seep out. Pour the chocolate mousse on top of the cake. Refrigerate the cake for 4 hours or overnight. Add fresh fruit on top before serving.

How to fold egg whites

I always think of that Schitts Creek episode now whenever I’m folding ingredients. 🤣

Here’s how to do it: Hold the spatula with your dominant hand and put your other hand on the bowl. In a wide circle go around the bowl with the spatula and flip your wrist to fold over the ingredients as you turn the bowl with your other hand. Keep going until there are no white streaks left. The point is to keep the whipped airy texture and not weigh it down with whatever you are mixing it with.

Do not mix regularly or it will deflate and ruin the lightness of the mousse.

Storing and freezer tips

Storing: To store the cake, keep it in the refrigerator. This cake stays fresh for up to three days. For best results, cover it lightly with plastic wrap to maintain its moisture and flavor.

Freezing: I dont recommend freezing this cake. The mousse layer wont survive the freezer. If you want to make this ahead- make and freeze the bottom fudge layer, then when you want to serve, make the mousse layer and add it to the defrosted cake.

I love when you share my recipes!!