Pumpkin Cookies with Butterscotch Chips

I have no idea where my Grandma got this recipe, but it's one of my all-time fall favorites.
Pumpkin Butterscotch Cookies
Makes about 24- 30 cookies
Ingredients:
1 c brown sugar, packed
1/2 c shortening
1 egg
1 c pumpkin
1 tsp vanilla
2 tsp baking powder
1 tsp baking soda
1/2 tsp salt
1 tsp cinnamon
2 1/4 cup flour
1 cup butterscotch chips

Directions:
- Preheat oven to 350 degrees F.
- Cream together first three ingredients.
- Add the next 6 ingredients & blend together.
- Stir in flour until just mixed together.
- Add chips last.
- Drop by rounded spoonful on to a greased cookie sheet (or use a silicon baking mat).
- Bake for about 20 minutes until firm, but not browned. 
- Remove to rack and let cool.