Good-Cooking - Chocolate Tweed Cake

Ingredients

• 2 cups mashed potatoes
• 3/4 cup butter
• 2 1/4 cups granulated sugar
• 3 eggs
• 1 3/4 cups all-purpose flour
• 2 teaspoons baking powder
• 1 teaspoon salt
• 1/2 cup milk
• 1 1/2 teaspoons cinnamon
• 1/2 teaspoon cream of tartar
• 1/2 teaspoon ground cloves
• 1/2 teaspoon nutmeg
• 2 ounces unsweetened chocolate, grated