Heat oven to 350°F. Grease and flour 13x9-inch pan. In small bowl, beat cream cheese and 1/4 cup sugar until smooth. Add egg, mint extract and food color; mix well. Set aside.
In 3- to 4-quart saucepan, melt 1 cup butter and 4 oz chocolate over very low heat, stirring constantly. Remove from heat; cool slightly. Stir in 2 cups sugar and 2 teaspoons vanilla. Add eggs 1 at a time, beating well after each addition. Stir in flour; mix well. Spread in pan. Carefully spoon cheese filling over brownie mixture. Gently cut through layers with knife to marble.
Bake 45 to 50 minutes or until set. Cool completely.
In heavy saucepan, heat 2 tablespoons butter, corn syrup and water to a rolling boil. Remove from heat. Add 2 oz chocolate; stir until melted.
Stir in 1 teaspoon vanilla and powdered sugar; beat until smooth. Frost cooled brownies. Cut into 9 rows by 4 rows. Cover and refrigerate any remaining brownies.