Good-Cooking - Cocoa Ripple Coffee Cake

Ingredients

• 1/2 cup butter or margarine
• 3/4 cup granulated sugar
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 2 eggs
• 1 1/2 cups all-purpose flour
• 2/3 cup milk
• 1/3 cup packed brown sugar
• 1/3 cup chopped walnuts
• 2 tablespoons unsweetened cocoa powder