Super Airy Blueberry Jam Mousse Filling

In a small bowl, combine 2 tbsp lemon juice and 2.5 tsp unflavored powdered gelatin. Stir briefly and let it bloom for 5 minutes.

In a small saucepan, gently warm 1 cup of blueberry jam over low heat until it becomes fluid and smooth (about 3-5 minutes). If the jam has large chunks of fruit, you may puree it briefly with an immersion blender for a smoother mousse.

Remove the warmed jam from the heat. Add the bloomed gelatin mixture into the hot jam and stir thoroughly until the gelatin is completely dissolved. Let the mixture cool to room temperature (do not let it chill or it will set).

In a large mixing bowl, combine 2 cups of cold heavy whipping cream, 1/4 cup powdered sugar, and 1 tsp vanilla extract. Whip until medium-stiff peaks form.

Gently fold the cooled blueberry jam mixture into the whipped cream in three separate additions using a rubber spatula. Be careful not to deflate the cream to maintain a super airy texture.

Immediately spread the mousse in a thick layer inside your prepared cake layers (using a cake ring or springform pan is highly recommended to hold the thick shape). Chill the cake for at least 2 hours in the refrigerator until the mousse is completely set.