Chocolate Chip Pumpkin Muffins

Preheat oven to 375 degrees F. Line a muffin pan with paper muffin liners, or spray generously with non-stick cooking spray.
In a medium bowl, combine flour, sugars, cinnamon, pumpkin pie spice, baking soda and salt. Mix to combine, then set aside.
In a large bowl combine pumpkin puree, eggs, vanilla, oil and butter. Mix until well combined. Add in dry ingredients and stir until just combined, but do not overmix.
Stir in chocolate chips or chunks.
Scoop ingredients into prepared muffin pan. Well should be filled about 3/4 of the way full. If desired, press additional chocolate chips or chunks into the top of each muffin.
Bake for approximately 20 minutes or until a toothpick inserted into the center comes out clean, or muffins springs back when lightly pressed.
Place on wire cooling rack for five minutes, then remove muffins from pan.