In a large bowl, combine the first six ingredients and mix well.
In a small bowl, mix together the egg, oil, and milk.
Add the wet ingredients to the dry ingredients and stir until combined. Stir in the raisins and walnuts.
Pour batter into a round or square baking pan that has been lightly oiled or nonstick-sprayed. Combine topping ingredients, and sprinkle it on top of the cake.