Preheat oven to 350 F. Prepare 9X13 inch baking dish with cooking spray.
In large mixing bowl, combine pumpkin puree, eggs, greek yogurt, brown sugar, and vanilla. Mix well. Stir in melted butter last.
On top of wet ingredients, add flour, baking soda, baking powder, salt, cinnamon, and butterscotch chips. Mix until combined and no flour pockets are left. Be careful not to overmix, or your cake will be tough and chewy.
Bake at 350 F for 30-33 min, or until inserted toothpick comes out clean. Light or glass pans may take a few minutes longer to bake than dark pans.