Preheat oven to 350 degrees F (175 degrees C). Grease mini-muffin or regular pan with cooking spray.

Sift together the flour, brown sugar, white sugar, cinnamon, nutmeg, ginger, baking soda, baking powder, and salt into a large bowl. Whisk together the eggs, butter, and pumpkin in a separate bowl. Mix the flour mixture with the egg mixture. Stir in the butterscotch chips; pour into each cup of the muffin pan to about 3/4 full.

Bake in preheated oven until a toothpick inserted into the center of a muffin comes out clean.Bake mini muffins for 10 to 12 minutes and large muffins for 15-18 minutes.