This is a super moist cake with a crispy topping. I got the recipe from a Penzey's spices catalog, submitted by Shelly Cooke. I tweaked it a little to make it a little bit tastier and easier to make. It is loaded with flavor, and is wonderful for a potluck.
Preheat oven to 350*. Grease and flour a 9x13 cake pan and set aside. Do not use a fragile pan as the topping is briefly broiled ( I use my pyrex glass pan).
In a medium sized bowl, combine the oats with the boiling milk (I nuked the milk and let the oats hang out in it for 10 minutes or so. I also used the regular oats). Let stand for 5-10 minutes (10 for reg. oats).
In a mixing bowl, cream together the butter and sugars until fluffy. Add the oats and mix. Add the eggs and vanilla and mix well. Add the baking soda, salt,and cinnamon and mix very well. Gradually add the flour in and mix well.
Pour into pan and bake for 30-35 minutes, until brown and a toothpick comes out clean. Remove from oven.
Just before you take the cake out of the oven, in a bowl combine the topping ingredients. I found that if I mix the butter, brown sugar, and the heavy cream and let set for a few minutes to melt the sugar some before adding the coconut it will spread easier on the cake. This will be very thick.
Now the cake is out of the oven, so preheat your broiler and move your oven rack so that the cake will be about 2 inches from the heating element.
Put spoonfuls of the topping mixture on top of the hot cake. Let set for a second or so until the topping starts to melt and then carefully spread the topping evenly on the cake. This step requires a bit of patience.
Once the topping is spread on the cake, put the cake under the broiler for a few minutes. Keep an eye on it, and when it is golden brown and bubbley it's done. Let set for a bit and then I find it's easier to cut if you cut it while still warm. The topping sets up and is kinda hard and crispy so you want to cut it before it sets. This cake is really yummy with ice cream!