Preheat oven to 180°C (350°F). Grease and flour two 18 cm round cake pans.
Whisk flour, baking powder, and salt in a bowl.
Cream butter and sugar in a large bowl. Add eggs one at a time.
Gradually mix in dry ingredients.
Divide batter between pans and bake for 25-30 minutes. Cool completely.
Mix on a high speed the eggwhites and sugar untill a nice and stiff mergenue. Whip seperatly the buter until nice airated. Mix both well and store on room temperature.
Heat & Combine:
Heat 200g passion fruit puree and 100g sugar in a saucepan until sugar dissolves.
Whisk Egg Mixture:
In a bowl, whisk 4 egg yolks (72g) and 40g cornstarch.
Temper Eggs:
Slowly pour the heated passion fruit mix into the eggs, whisking continuously.
Cook & Add Butter:
Cook the mixture until thickened. Remove from heat and whisk in 150g softened butter.
Melt Ingredients:
In a heatproof bowl, combine 200g finely chopped white chocolate, 80g unsalted butter, and 100g heavy cream.
Heat:
Melt the mixture over a double boiler or in short bursts in the microwave, stirring until smooth.
Cool:
Let the glaze cool slightly before using it on your desired dessert.
Cut the baked sponge in 3 layers and spread on a thin layer of cremeux, pipe on a layer of buttercream en repeat this once. Smooth out the sides and top of the cake with butter cream and place for 5 hours in the freezer. Glaze the cake directly out of the freezer. Decorated. (see picture)