In a bowl, cover rolled oats with boiling water and let stand for 1 1/2 hours or until completely cooled.
Combine the flour, baking soda, cinnamon, salt and nutmeg. Set aside. In a large mixing bowl, beat the butter until it is creamy, then mix in the brown and granulated sugars. Beat until fluffy. Beat in eggs and vanilla. Stir in the cooled oat mixture and mix well. Stir in the dry ingredients, about a third at a time. When finished you will have a stiff batter.
Spread the batter in a greased and floured 13"x9" baking dish. Bake for 50-60 minutes or until a tester inserted in the center comes out clean.
For the topping, stir together the butter and cream, then blend in the coconut, brown sugar and nuts. Spread the mixture over the baked cake. Broil until the topping is bubbling, about 2 to 3 minutes.