Preheat oven to 350°. In a medium bowl, blend the sugars, eggs, pumpkin and oil until smooth. Add the dry ingredients and mix just until combined. Do not over mix!
Add paper liners to 12 muffin tins and fill each liner 3/4 full with batter.
Meanwhile, melt 1 c. of the chocolate chips by microwaving in 30 second intervals, stirring well after each 30 seconds. Top each muffin tin with a heaping Tablespoon of melted chocolate and using a butter knife gently swirl it into the center.
Top the muffins with the remaining chocolate chips.
Bake at 350° for 18-20 minutes, or until a toothpick inserted in the center comes out clean.