Preheat oven to 350°F.

Prepare 3 8-in round cake pans by lightly greasing and flouring them. Set aside.

In the bowl of an electric mixer, beat sugar and butter until light and fluffy.

Add the eggs, one at a time. Continue beating on high speed for about 3 more minutes.

In a separate large bowl, sift together flour, baking powder, and salt.

Reduce speed. Add juice and mineral water.

Gently stir in dry ingredients.

Evenly distribute batter into prepared cake pans and bake 30-35 minutes, or until toothpick inserted into the center comes out clean.

Remove from oven and let cook in pans for 5 minutes. Remove cakes from pans and let cool completely on a cooling rack.

In a small bowl, bloom gelatin by sprinkling it over 3 tbsp water. Set aside for 5-10 minutes.

In another bowl, beat egg whites until firm peaks.

In a blender, blend condensed milk and passion fruit concentrate.

Stir in cream and dissolved gelatin.

Transfer to large bowl and fold in egg whites.

Cover and chill in refrigerator until firm.

Combine sugar and water in medium heavy-bottomed saucepan.

Simmer without stirring until syrup-like.

In the bowl of an electric mixer, beat egg whites until soft peaks form.

On medium speed, carefully add sugar syrup in a slow steady stream down the side of the bowl.

Beat on high speed until fluffy, light, and cool (about 7 minutes).

Line an 8-inch springform pan with plastic wrap or aluminum foil.

Place on cake layer in pan, then brush layer with 3 tbsp of passion fruit juice. Add 1 cup of mousse to layer and spread evenly.

Gently place second layer and repeat process.

Add final layer and brush with remaining passion fruit juice.

Wrap tightly with plastic wrap and refrigerate until set (minimum 2 hours).

Remove from refrigerator, and gently remove from pan.

Cover cake with frosting and serve!

Add pineapple flowers as a decoration. Instruction can be found here.