In small bowl, mix rolled oats with 1 cup hot water. Let cool. In large bowl, cream butter with sugar; beat in egg, yogurt and vanilla. Stir in oats. In separate bowl, mix flour, cocoa, baking powder, baking soda and salt. Stir in oats mixture just until combined. Do not overmix. Pour batter into greased 8-inch square cake pan. Bake in 350F 180C oven for 30-35 minutes or until centre springs back when lightly pressed. Let cool. Icing: Beat together icing sugar, cocoa and cream cheese; beat in milk until smooth. Spread over cake. Per serving: about 120 calories, 2 g Protein, 3 g fat, 21 g carbohydrate