I found this recipe from allrecipes.com. I have tried different oatmeal cake recipes and this is by far the best one. I make one for my dad every year for his b-day and he just loves it and can never stop talking bout how good and moist it is.
In a small bowl pour boiling water over oats. Mix well and cool.
In a large bowl combine butter or margarine, 1 cup brown sugar, 1 cup white sugar, eggs, flour, baking soda, spices and salt. Add cooled oatmeal mixture and stir to combine. Pour batter into pan.
Bake for 35 minute.
While cake is baking combine 1/2 cup white sugar, 1/4 cup brown sugar, coconut, melted butter or margarine, vanilla and cream in a mixing bowl. Remove cake from oven and turn on broiler. Drop mixture by small spoonfulls on top of cake. Spread evenly nad carefully. Broil for 2-5 minute until topping is bubbling and lightly browned.