In a stand mixer fitted with the paddle attachment, combine egg, butter, sugars, vanilla and beat until creamed, about 4 minutes.

Add oats, flour, cinnamon, baking soda, and salt, then beat on low until just combined, about 1 minute.

Stir in chocolate chips and optional raisins or nuts on low speed until combined, about 30 seconds.

Using a cookie scoop or hands, form approximately 12 balls, flatten slightly, and place on a tray. Refrigerate for at least 2 hours.

Preheat oven to 350°F. Line baking sheets with Silpat or spray with cooking spray. Arrange dough balls with 2 inches apart.

Bake for about 11 minutes until edges are set and tops are slightly glossy. Cool on baking sheet for 10 minutes before serving.