Preheat oven to 350°F. Make cake mix according to package directions. In another bowl, mix egg, sugar and cream cheese till blended, then stir in chocolate chips. Line muffin pan with liners, fill with batter and bake according to time on cake mix box. Halfway through baking, take out muffins. Drop one teaspoon of cream cheese mixture on top of each muffin. Return muffins to oven and finish baking. Makes 24.