In a large bowl, beat eggs on high speed for 5 minutes or until thick and lemon-colored. Gradually add sugar, beating until mixture is light and fluffy. Beat in vanilla. Combine flour and baking powder; gradually add to batter; beat at low speed until smooth.

In a small saucepan, heat milk and butter just until butter is melted. Gradually add to batter; beat just until combined.

Pour into a greased 13-in. x 9-in. baking pan. Bake at 350° for 30-35 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack.