Combine flour and brown sugar; stir well. Cut in small pieces of butter with a pastry blender or 2 knives until mixture resembles coarse meal. Press mixture firmly into bottom of an 8-inch square pan coated with cooking spray. Bake at 350° for 8 minutes. Remove from oven.
Place fudge topping in a small microwave-safe bowl. Microwave at HIGH 1 minute or until thoroughly heated, stirring after 30 seconds.
Beat cream cheese at medium speed of a mixer until smooth. Gradually add sugar, beating well. Add egg and next 3 ingredients, beating well. Pour batter over prepared crust. Drizzle fudge topping over batter. Using the tip of a knife, swirl fudge into batter. Bake at 350° for 20 minutes or until set. Let cool completely in pan on wire rack.