Make the cake batter according to the box instructions.
Bake in two circular baking pans.
Once fully cool, drizzle 2 tbsp of the Prosecco syrup over the top and the bottom of both cakes.
Place the cakes in the fridge to cool and so that the syrup can absorb.
Carefully frost the first layer of your cake with half of the buttercream, then sprinkle on a layer of fresh berries.
Place the second layer of cake on top of the berries and use the remaining buttercream to carefully frost the top of the cake.
Finish the cake by decorating the top with more fresh berries and flowers, if you have them on hand!