Start by beating together the softened butter, brown sugar, and granulated sugar in a large bowl until the mixture is light and fluffy, about 3-4 minutes with an electric mixer.
Beat in the eggs one at a time, ensuring each is fully incorporated, then stir in the vanilla extract.
In a separate bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg.
Gradually add the dry ingredients to the butter mixture, mixing on low speed just until combined. Avoid overmixing.
Gently fold in the rolled oats and butterscotch chips using a spatula.
Preheat oven to 350°F (177°C). Line baking sheets with parchment paper or silicone mats. Scoop dough with a cookie scoop or tablespoon, spacing about 2 inches apart. Bake for 10-12 minutes until edges are golden but centers are slightly soft.
Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.
