In a large bowl, combine eggs, butter and vanilla. In a separate bowl, combine the dry ingredients. Add to egg mixture. Mix well. Stir in chocolate chips. Set aside 1 cup of batter for the topping. Spread remaining batter into a 9 x 13 pan.
In a small bowl, beat cream cheese, peanut butter and sugar until smooth. Add egg and milk and mix. Carefully spread over batter. Drop reserve batter over the filling. Cut knife through batter to swirl.
Bake at 350° for 35-40 minutes or until inserted toothpick comes out clean.