||Preheat oven to 350 degrees. Mix cake mix according to package directions. Add vanilla extract. Pour into greased/sprayed 12-cup Bundt pan.
Beat together cream cheese and sugar until fluffy. Add egg and mix well. Stir in chocolate chips. Spoon this mixture into the center of the cake batter. Keep this mixture away from the sides of the pan. Swirl with a knife.
Bake for 40 to 45 minutes. Cool in pan for 10 to 15 minutes. Then, remove the cake from the pan to cool completely.