Preheat oven to 350. Line 24 muffin cups with paper liners.
Beat cream cheese and sugar together in a large mixing bowl.
Add vanilla and egg, beat for 30 seconds, or until well combined.
Stir in chocolate chips and set aside.
Place the cake mix, water, oil, and eggs in a large mixing bowl. Blend with electric mixer on low for 2 minute, scraping sides down.
Increase mixer speed to medium and beat for 2 more minutes, or until batter looks thick and well combined.
Fill each muffin cup 2/3 full.
Spoon a heaping teaspoon of filling into the center of each muffin. (The filling will sink into the muffins as they bake).
Bake muffins 23 to 27 minutes, or until the spring back when lighly pressed with your finger.
Remove from oven and cool in pan for 5 minutes. Run a butter knife around the edge of the liners and lift the muffins up from the bottom, using the knife. Place on wire rack to continue to cool for at least 15 minutes before serving.