Place cooled cake on serving plate. In 1-quart saucepan, heat 1/4 cup butter over medium heat, stirring occasionally, until golden brown. Pour browned butter into medium bowl; stir in powdered sugar, vanilla and milk, 1 tablespoon at a time, until spreadable (mixture will thicken as it cools). Let stand 1 to 2 minutes or until slightly cool; stir. Drizzle over cake.