For cake, grease an 8x8x2-inch baking pan; set aside. In a large bowl, combine granulated sugar, flour, and baking powder. In a small bowl, combine eggs, the 1/2 cup milk, and the vanilla. Add all at once to flour mixture; mix well. Turn into prepared pan. Bake in a 375 degree F oven about 20 minutes or until a toothpick inserted near center comes out clean.
Meanwhile, for topping, in a medium saucepan, combine coconut, brown sugar, nuts, butter, the 3 tablespoons milk, and the salt. Cook and stir until butter is melted and brown sugar is dissolved. Spoon over hot cake. Increase oven temperature to 400 degrees F. Bake about 10 minutes more or until topping is golden. Cool in pan on wire rack. Serve warm or at room temperature. Makes 9 servings.