This incredible Blueberry Mousse Cake combines a tender vanilla cake with a fluffy blueberry mousse topping that’s light, creamy, and packed with fresh berry flavor.

Blueberry mousse cake cooling on a wire rack.

If you enjoy fruity desserts that aren’t overly heavy, this cake is a perfect option. The blueberry mousse is so smooth and airy that you may want to enjoy it all on its own.

A Perfect Dessert for Gatherings

This recipe works wonderfully for parties, potlucks, and picnics because it’s simple to assemble and doesn’t require stacking complicated cake layers. It also travels well since you can keep the dessert directly in the baking pan and slice it when ready to serve.

Unlike my strawberry mousse dessert, this version includes a true cake base. I used the same soft vanilla cake from my strawberry shortcake recipe but baked it in a square pan rather than a round one. The mousse layer is inspired by the strawberry mousse version, although this recipe uses a thinner layer spread neatly across the top of the cake.

The combination of fluffy cake and delicate mousse creates a dessert that feels light, fresh, and pleasantly sweet without being overwhelming. It’s very easy to go back for another slice.

If rich chocolate desserts are more your style, chocolate coffee mousse, chocolate mousse cake, and Nutella mousse cake are also excellent choices for something extra indulgent.

Why You’ll Love This Recipe

The yellow cake is soft, moist, and fluffy with a delicate crumb that almost melts in your mouth.

The blueberry mousse has a balanced flavor with natural berry sweetness that doesn’t overpower the dessert.

Another great feature is how customizable the recipe can be. You can replace the blueberries with the same amount of other fruits such as strawberries, peaches, pineapples, mangos, and more.

Ingredient Notes

For exact measurements and the complete instructions, check the recipe card located at the bottom of the original post.

Butter

Unsalted butter provides the best flavor and texture for the cake.

Sugar

Regular granulated sugar is used in both the cake and the mousse filling.

Eggs

You’ll need two room-temperature eggs for the batter.

Buttermilk

Do not replace the buttermilk. It adds richness and moisture that regular milk cannot provide, while sour cream is too thick for this recipe.

Vanilla

Pure vanilla extract gives the best overall flavor.

Flour

Cake flour creates a soft and tender texture. Using all-purpose flour will change the final result.

Baking Powder and Baking Soda

These leavening ingredients work together with the buttermilk to help the cake rise properly.

Salt

A small amount balances the sweetness of the dessert.

Blueberries

Fresh seasonal blueberries are ideal because they usually have better sweetness and flavor than frozen berries.

Gelatin

Unflavored gelatin powder helps stabilize and set the mousse layer.

Heavy Cream

Use heavy cream or heavy whipping cream so the mixture can whip into stiff peaks properly.

Powdered Sugar

A little powdered sugar lightly sweetens the whipped cream.

Step-by-Step Instructions

Prepare the Cake

Beat the butter and sugar together until creamy, then mix in the eggs and vanilla extract. Add the buttermilk and stir until combined.

Next, add the cake flour, baking powder, baking soda, and salt. Mix gently until the batter comes together.

Pour the batter into a 9-inch square baking pan and bake until a toothpick inserted into the center comes out with only a few moist crumbs attached. In my oven, this usually takes around 25 minutes.

Make the Blueberry Mousse

Blend the blueberries into a puree, then cook them with sugar until the mixture thickens slightly.

Add gelatin that has been softened in water, stir well, and transfer the mixture to a heatproof bowl. Refrigerate until completely cooled.

Whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form. Carefully fold the chilled blueberry mixture into the whipped cream.

Spread the mousse evenly over the cooled cake while it remains in the lined pan. Refrigerate for several hours until the mousse becomes firm.

Helpful Tips

Avoid baking the cake too long, as overbaking will make it dry. Begin checking the cake around the 20-minute mark. The center should leave just a few moist crumbs on a toothpick.

When combining the blueberry mixture with the whipped cream, fold gently instead of stirring aggressively. Rough mixing can deflate the whipped cream and reduce the mousse’s airy texture.

Fresh, in-season blueberries will give the mousse the best flavor and natural sweetness.

Try not to substitute ingredients in this recipe. The ingredient balance has been carefully tested to create the softest cake and smoothest mousse possible. Changing ingredients may affect the final texture.

Frequently Asked Questions

My blueberry mixture didn’t become thick like jam. Is that normal?

Yes, that’s completely fine. The blueberry mixture should remain fairly loose rather than becoming thick like traditional jam. Once mixed into the whipped cream and chilled, the gelatin will help the mousse set properly.

Can I prepare the cake in advance?

Definitely. The cake layer can be baked ahead of time, cooled completely, and wrapped tightly in plastic wrap. Store it in the refrigerator for up to one day or freeze it for up to 30 days before using.

Can I make the blueberry filling ahead of time?

Yes, the blueberry mixture can be prepared early. For the best freshness and flavor, it’s recommended to use it within one or two days.