We had this at our wedding for the cake. Such a good cake!
Cake:
Pour 1 c boiling water over 1 c oatmeal in mixing bowl. Add 1/2 c butter. Let stand until melted.
Add:
2 beaten eggs
1 c brown sugar
3/4 c sugar
1 1/3 c flour
1 tsp baking soda
1 tsp cinnamon
1 tsp nutmeg
1/2 tsp salt
2 tsp vanilla
Mix well, pour in greased cake pan 9x13. Bake at 350 for 35 minutes.
Frosting:
Cook in saucepan- low to medium heat
1 c milk
4 TBS flour
Make a paste of above, stirring constantly until thick. (If you have a stick blender, it works great)- 12 to 15 minutes. Refrigerate until VERY COLD.
In a mixing bowl:
1 stick butter - do not use Fat Free or LITE
1/2 c shortening
1 c sugar
1 tsp vanilla
Mix until well blended and creamy. I mix butter and shortening, then add sugar and after all is mixed well, then vanilla. I usually beat it on HIGH for at least 5 minutes. Add to this mixture the cold milk/flour mixture and beat thoroughly.