Preheat oven to 350°F. Line a 12 cup muffin pan with tulip paper liners. If you don’t have tulip papers, grease or line 12 jumbo muffin cups or 18 regular muffin cups.
Prepare cream cheese topping: In a small mixing bowl, beat together cream cheese, sugar and salt until smooth. Add egg and vanilla and beat until incorporated. Add flour and beat just until smooth. Set aside.
Prepare muffin batter: In a large mixing bowl beat together butter, cocoa powder, sugar, baking powder, salt and vanilla until fluffy. Beat in eggs, then stir in milk and sour cream. Mix in flour, then chocolate chips.
Divide batter equally between the muffin cups. Put a dollop of cream cheese mixture on top of the muffin batter.
Bake for 30 minutes, or until a toothpick inserted in center comes out without crumbs on it – chocolate is ok. Remove from oven, cool on wire racks 10 minutes, remove from pan to wire racks and cool completely.
Notes
Tip: Save about ¼ cup of the chocolate chips to sprinkle on top of the chocolate muffin batter.