Heat oven to 350°F (180ºC). Line 24 medium muffin C. with paper baking cups. In large bowl, beat 1/2 C. (125 mL) sugar and cream cheese until smooth. Beat in egg until smooth. Stir in chocolate chips. Set aside.
In large bowl, beat remaining ingredients on high speed for 3 minutes. Reserve 1 1/4 C. (300 mL) of batter.
Fill each muffin C. about 1/3 full. Spoon about 1 tablespoonful (15 mL) of cream cheese mixture onto the batter in each cup. Top each C. with reserved batter.
Bake at 350°F (180ºC) for 22 to 25 minutes or until toothpick inserted in centre comes out clean. Serve warm or cold. Cover and refrigerate any leftovers.