Mix cake according to package directions ( lower-fat version, replace the oil with applesauce and add 2 Tbls. flour).
Fill paper baking cups in muffin pans 2/3 full.
Cream the cream cheese with sugar, beat in egg and salt. Stir in chocolate chips. Drop 1 rounded teaspoon of this mixture into each cupcake.
Bake 19 to 22 minutes at 350 degrees.
Final Comments
Note: These make excellent lunch box desserts, because they don't need frosting. The cream cheese sinks to the bottom, and is like frosting on the inside. Can also be baked as a cake instead of cupcakes, just drop rounded teaspoons of cream cheese mixture randomly around cake and bake in 9x13-inch pan for 35 minutes at 350 degrees.