Prep: 1. Bring butter to room temperature. 2. Preheat the oven to 350. Grease a 9x13 inch baking dish. 3. Combine the water and the oatmeal and allow to soak while you prepare the remaining ingredients. Make: 1. Using an electric mixer, cream 1/2 cup butter, 1 cup of the brown sugar, and white sugar until light and fluffy, about 2 minutes. Beat in the eggs. 2. In a separate bowl, whisk together the flour, cinnamon, baking soda and salt. Add half of the flour to the creamed butter mixture, followed by the soaked oatmeal, then the remaining flour, mixing between additions. 3. Pour into the prepared baking dish and bake until set, 35-40 minutes. 4. Shortly before cake is done, prepare the topping: In a saucepan combine 1/2 cup butter, 1 cup brown sugar and milk. Bring to a boil, stirring consistently. Let boil for 1 minute then add coconut and remove from heat. 5. Once the cake is done, remove from oven, and then preheat the broiler. 6. Pour topping over the cake, spread, then broil for one minute, careful to not let it burn.
Depending on your sweet tooth you can reduce the sugar in this by up to half, or omit the white sugar entirely. You can also easily halve this recipe and use an 8x8 pan.