Place the egg whites in a large bowl, reserving the egg yolks for later use. Beat the whites until stiff.
Gently fold the sugar and almond meal through the stiffened egg whites.
Grease a 9 inch/24 cm springform cake pan (you can also line the bottom of the pan with baking paper) and pour in the batter.
Bake at 350° F/180° C for 25 - 30 minutes. Let it cool completely in the pan before trying to remove it, otherwise the cake may not pull away from the sides as easily.
For the cream topping place all ingredients in a small saucepan and cook on medium heat, stirring constantly until it comes to the boil and thickens.
When at room temperature add butter to the custard cream and beat by hand with wooden spoon until combined and smooth.
When cake has cooled spread custard cream over the top and decorate with toasted, flaked almonds.Vaersegod!! (Va sha gu) which means Bon Appetit in Norwegian :)