Soak the gelatin in cold water according to the instructions on the package.

Pour strawberry jam into a small saucepan, add cold milk and the softened gelatin, place over low heat and heat, stirring constantly, until the gelatin has completely dissolved.

Place the cold cream in a deep bowl, add the sugar, and beat until soft peaks form.

Add the cooled strawberry jam to the whipped cream and mix well.

Cut the strawberries in half.

Place the prepared sponge cake on the bottom of the cake tin. Arrange the strawberry halves around the tin, on top of the cake, pressing them into shape.

Carefully pour the whipped cream and strawberry jam over the prepared cake base. Gently shake to release any excess air bubbles.

Flatten the surface of the mousse and refrigerate for at least 6 hours, preferably overnight.

Decorate the cooled mousse cake to your liking, for example: strawberry jelly, fresh strawberries and blueberries, whipped cream.

Carefully remove the finished cake from the mold and place it on a flat plate.