Method
Preheat oven to 350°F and line two baking sheets with parchment paper.
Cream together the softened butter, brown sugar, and granulated sugar until light and fluffy, about 2–3 minutes.
Beat in the eggs one at a time, then stir in vanilla extract.
In a separate bowl, whisk together flour, baking soda, baking powder, salt, and cinnamon. Gradually mix into wet mixture until just combined.
Fold in oats and optional mix-ins like raisins or chocolate chips.
Scoop heaping tablespoons of dough onto prepared sheets, 2 inches apart.
Bake for 10–12 minutes until edges are golden and centers are slightly soft.
Cool on sheet for 5 minutes, then transfer to wire rack to cool completely.
Notes
Swap raisins for dried cherries, or go dairy-free with plant-based butter. Chill the dough for 30 minutes for thicker cookies, and store with a slice of bread to keep them soft longer.