Preheat oven to 180 degrees C. Grease and flour a 20cm square pan. In a medium bowl combine boiling water and oats. Stir, then set aside for 40 minutes. Sift together the flour, bicarb soda, cinnamon, nutmeg and cloves. Set aside.
In a large bowl, cream together 125g butter, 1 cup brown sugar and 1 cup white sugar until light and fluffy. Beat in 2 eggs one at a time then stir in the vanilla. Beat in the oat mixture. Gradually beat in the flour mixture. Pour batter into prepared pan.
Bake in the preheated oven for 50 minutes, or until a toothpick inserted into the centre of the cake comes out clean. While cake is baking prepare topping.
In a medium bowl cream 3 tablespoons butter and 3/4 cup brown sugar until smooth. Beat in 1 egg and 3 tablespoons milk. Stir in coconut and pecans. Spread over hot cake. Return cake to oven for 10 minutes or until the topping is golden. Cool and cut into squares.