Batter: Melt together chocolate and butter in a heavy saucepan over low heat; stir in sugar until dissolved. Remove from heat and whisk in eggs, vanilla and flour until blended. Drop by teaspoonfuls onto a heated waffle iron; bake according to manufacturer's instructions. Top with Chocolate Frosting.
Chocolate Frosting: Melt chocolate and butter in a heavy saucepan over low heat; remove from heat and add milk and vanilla. Mix in powdered sugar to desired consistency.