Preheat oven to 350 degrees F.

Cream together butter (or shortening), brown sugar, and granulated sugar.

Add eggs and mix.

Add flour, baking soda, salt and cinnamon. Mix until combined.

Add oats and mix until combined.

Add chocolate chips (see note below) and mix until combined.

Spoon heaping teaspoonfuls onto a greased cookie sheet and bake for 10 minutes. Makes about 4 dozen cookies.

Notes:

You can substitute any number of mix-ins here: raisins, dried cranberries, chopped nuts, coconut, etc. One of my favorite combos is half chocolate chips, half dried cranberries.

I typically refrigerate the dough for a bit before spooning onto the cookie sheet to help prevent the cookies from spreading too much. This might not be necessary, but it’s how I’ve always done it. I normally return the dough to the fridge between sheets.