Preheat oven to 360F. Arrange the parchment paper at the bottom of the 9-inch cake pan.
Beat the egg whites with an electric mixer at high speed until fluffy. Add sugar while mixing the egg whites.
Sift in the flour and baking powder. Then add the flour in the egg white mixture and fold in with the spatula.
Pour the batter into the baking pan. Bake for 15-20 minutes.
Now start preparing the white chocolate mousse by mixing the heavy cream at high speed until stiff.
In another bowl, mix egg whites at high speed until stiff. Melt the white chocolate in the microwave but make sure to not overheat and burn the chocolate.
Mix the cream cheese and sugar with the electric mixer at medium speed until smooth and creamy.
Mix gelatin with boiling water. Once melted, add it to the cream cheese mixture and mix until combined, then add white chocolate. Add whippedcream and mix with a spatula. Finally, add egg whites mixture and mix until well combined.
Now pour the white chocolate mousse over the cakeand let it set in the fridge for at least 2 hours.
Arrange the strawberry slices layer on top of the cake. Combinegelatin and boiling water. Add strawberry sauce or jam and let it cool for few minutes. Then pour it over the strawberries on top of the cake.
Place the cake in the fridge for another 1 hour before serving. Delicious white chocolate mousse cake is ready. Enjoy!