Heat oven to 375°. Grease 12 medium muffin cups, 2 3/4x1 1/4 inches, with shortening; or line muffin cups with paper baking cups and spray with cooking spray.
Mix flour, 1/3 cup sugar, the cocoa, baking powder and salt in large bowl. Stir in egg, milk, butter and chocolate chips just until blended. Fill muffin cups about 2/3 full.
Mix cream cheese, melted baking chips and 1 tablespoon sugar in small bowl until smooth. Stir in cranberries. Drop spoonfuls of cream cheese mixture onto muffin batter, pressing down slightly.
Bake 20 to 25 minutes or until muffins are puffed and cream cheese mixture is light golden brown. Remove from pan to wire rack. Cool 15 minutes before serving.