Preheat oven to 350 degrees F (175 degrees C). Lightly butter muffin tins and set aside.
Beat together the cream cheese, egg, sugar and salt. Stir in chocolate chips and set aside.
In a separate bowl, sift together the flour, sugar, cocoa, baking soda and salt. Add the water, oil, vinegar, and vanilla. Beat until well combined. Batter will be thin.
Fill muffin cups 1/3 full with the chocolate batter. Top each one with a spoonful of cream cheese mixture.