Heat oven to 350°F Grease bottom and sides of 13x9-inch pan with shortening; lightly flour. In small bowl, beat cream cheese and 1/4 cup sugar with spoon until smooth. Stir in 1 egg, the mint extract and food color until well mixed; set aside.
In 3-quart saucepan, melt 1 cup butter and 4 oz chocolate over very low heat, stirring constantly; remove from heat. Cool 15 minutes or until slightly cooled.
Stir 2 cups sugar and 2 teaspoons vanilla into chocolate mixture. Add 4 eggs, one at a time, beating well with spoon after each addition. Stir in flour. Spread in pan. Carefully spoon cream cheese mixture over brownie mixture. Lightly swirl cream cheese mixture into brownie mixture with knife for marbled design.
Bake 45 to 50 minutes or until set. Cool 30 minutes at room temperature. Refrigerate 1 hour.
Meanwhile, in 2-quart saucepan, heat 2 tablespoons butter, the corn syrup and water to rolling boil, stirring frequently; remove from heat. Stir in 2 oz chocolate until melted. Stir in 1 teaspoon vanilla and the powdered sugar. Beat with spoon until smooth. Frost chilled bars with Chocolate Frosting. For bars, cut into 6 rows by 6 rows. Store covered in refrigerator.