Topping:
1/2 cup flour
1 1/2 cups sweetened flaked coconut
1/2 cup brown sugar
1 1/2 T cinnamon
6 T butter, melted
Combine all ingredients and set aside.
Make the batter:
5 large egg yolks
1/4 cup brown sugar
1/3 cup sugar
1 1/2 tsp vanilla
Beat above ingredients until mixture is thick and a pale yellow color — about 2 minutes. Mix in 3/4 cup softened butter and 1/2 cup sour cream. Add 1 3/4 cup flour and 1 tsp baking powder.
Pour batter into a buttered 9″ springform pan and top with coconut topping. Bake at 325 degrees for 55 to 60 minutes. Cool. Release the cake from the pan and serve warm. Delish!!!