Gluten Free Chocolate Custard Cake

Preheat oven to 325 F degrees.
Line 8-inch x 8-inch baking dish with parchment.
Separate eggs and add the egg whites to a mixer and beat egg whites stiff.
In a separate bowl, beat the egg yolks & sugar until light. Add butter and vanilla. Beat for two mins. Add cocoa and flour and mix until fully incorporated.
Gradually add milk and beat until well mixed.
Add the egg whites (a third at a time) and gently fold them in using a spatula, repeat until all egg whites are folded in. Be gentle, take your time and fold them in until you no longer have large egg white clumps.
Pour batter into baking dish and bake for 60 min or until the top is lightly golden.
Cool to room temp and then chill.
Dust heavily with powdered sugar.