In a stand mixer, beat eggs, butter, brown sugar, white sugar, vanilla on medium-high until light and fluffy, for 5 minutes. Scrape sides of bowl if needed.
Add oats, flour, cinnamon, nutmeg, baking soda, and salt. Beat just until incorporated. Add in butterscotch chips and beat just to immediately incorporate.
Using a 1-inch cookie scoop, scoop out all dough into balls. Place balls on wax or parchment paper and refrigerate for at least 1 hour. You can also keep covered in refrigerator for up to 5 days.
Preheat oven to 350F, line baking sheets with parchment. Place cookie balls on baking sheets, spaced about 2 inches apart.
Bake for 9 to 10 minutes, or until edges are set and tops are barely set. Cookies may not appear to be done, but they firm up as they cool.
Cool on cookie trays for about 5 minutes before transferring to a wire rack.
Store cookies in airtight container at room temperature for up to a week.
Allow cookies to cool on trays for about 5 minutes before transferring to a wire rack to finish cooling.
Recipe by Sweet Dash of Sass at https://sweetdashofsass.com/2015/12/oatmeal-butterscotch-cookies/