Preheat oven to 180 degrees C. Grease a 20x30cm pan.
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, bicarb soda, spices and salt. Add cooled oatmeal mixture and stir to combine. Pour batter into pan.
Bake for 35 minutes.
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 grill. Drop mixture by small spoonfuls on top of cake. Spread evenly and carefully. Grill for 2 to 5 minutes, until topping is bubbling and lightly browned.