Cream together the Crisco and sugar (white and brown).
Add eggs one-at-a-time and beat after each egg.
Sift together flour, then sift again, adding soda, salt, cinnamon & nutmeg.
Whip up the oats and add the vanilla. Add this to the creamed mixture. Add flour gradually.
Bake in a 9" X 13" non-stick baking pan, at 350º for 25 min.
For topping: Mix together the melted butter, brown sugar, coconut, pecans and egg yolk. Add just enough milk to make the mixture thin enough to spread easily. Spread over the top of the cake and return to the oven just long enough to brown the topping.
Serve it plain, or with ice cream or whipped cream.