Preheat oven to 350 degrees F. Coat a 9"x13" baking dish with cooking spray.In a large microwaveable bowl, place baking chocolate and butter. Microwave on high 2 to 2-1/2 minutes, stirring after each minute, until chocolate and butter are completely melted. Beat in 2 cups sugar, 3 eggs, and the vanilla, until blended. Stir in flour, then spread batter in prepared baking dish.
In a medium bowl, beat cream cheese, the remaining sugar, and remaining egg. Stir in candy. Drop by dollops over batter. With a knife, swirl the batter to the top to create a marbled effect. Bake 40 to 45 minutes, or just until set. Cool completely in baking dish on a wire rack. Cut into bars.