In a bowl add oats and boiling water; stir. Let it stand for 20 minutes.
2In a mixer add butter, sugar, brown sugar; beat. Add eggs; beat. Add baking soda, baking powder, salt and cinnamon; beat. Add cooled oat mixture; beat. Add flour slowly; beat. Pour batter into greased 9x13 cake pan. Bake 35-45 minutes, test with toothpick for doneness. Cool completely.
3Frosting: In a saucepan over low heat add butter to melt. Add brown sugar; stir until dissolved. Add coconut, nuts and vanilla; stir about 5 minutes. Frost cake. Once it cools to room temperature, refrigerate the cake.