Preheat oven to 350 degrees. Line the bottom and sides of a 9x13" baking dish with aluminum foil. Spray with non-stick spray and set aside.

In a large microwave-safe bowl, combine the chocolate and butter. Microwave on high in 30-second intervals, stirring after each interval, for about 2 minutes total. Whisk mixture until it is smooth, and then whisk in the 2 cups of sugar. Add the eggs, 1 at a time, whisking just until blended after each addition. Whisk in the food coloring and 1 teaspoon vanilla extract. Gently stir in the 1 1/2 cups flour and the salt, stirring just until all ingredients are blended. Pour batter into the prepared pan.

For the cream cheese topping, use an electric mixture to beat together the cream cheese and 1/4 cup sugar until mixture is light and fluffy. Add the egg whites and remaining 1 teaspoon vanilla, and beat until smooth. Stir in the 2 tablespoons flour until smooth. Drop the mixture by heaping tablespoons onto the prepared batter in the pan; use a knife to swirl the cream cheese mixture through the batter.

Bake at 350 for 30-35 minutes, or until a wooden skewer inserted in the center comes out clean. Cool completely in pan on a wire rack before lifting the brownies from the pan using the foil as a "sling." Remove foil, and cut the brownies into squares.