To make an old-fashioned oatmeal cake, mix granulated sugar, brown sugar and butter in a large bowl. Add eggs, vanilla, oatmeal, flour, baking soda, baking powder, salt, cinnamon and nutmeg. Pour the batter into a 13-by-9-inch pan, and bake at 350 degrees Fahrenheit for 45 minutes.
To create an oatmeal cake topping, mix half and half, butter and brown sugar in a small bowl. Add shredded dried coconut and chopped nuts to the mixture. After the oatmeal cake is done, spread the topping over the cake. Turn the oven setting to broil. Keep the cake in the oven between one and two minutes, or until the top turns brown. Allow the cake to cool for up to one hour before serving.
Additional toppings include maple syrup glaze and brown sugar frosting. To create a maple syrup glaze, combine maple syrup and confectioner's sugar. After the oatmeal cake cools, slice and use a whisk to drizzle the glaze over individual pieces.
To make brown sugar frosting, heat brown sugar, milk and butter in a small sauce pan. Remove from heat, and add confectioner's sugar and vanilla. After the cake cools, spread the frosting over the entire cake. For added sweetness, serve oatmeal cake with vanilla ice cream or whipped cream.