Preheat oven to 325°F. Line 18 (2-1/2 inch) muffin cups with paper baking cups.
Beat butter and cream cheese in large mixer bowl until creamy. Add sugar and beat 1 to 2 minutes until light and fluffy. Beat in eggs, one at a time, until well blended, then corn syrup and vanilla.
Sift or whisk flour, cocoa, baking powder and salt together. Gradually add dry ingredients to butter mixture, mixing after each addition until combined. Stir in melted chocolate. Portion batter evenly into prepared muffin cups. Sprinkle a few chocolate chips evenly over each cupcake.
Bake 28 to 33 minutes or until center is set and toothpick inserted in center comes out clean. Cool in pan 5 minutes. Remove to wire rack to cool completely.