Preheat the Oven: Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats for easy cookie removal.
Cream the Butter and Sugars: In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar using an electric mixer or by hand with a whisk. Beat until light and fluffy, about 3 minutes.
Add the Eggs and Vanilla: Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
Combine Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, baking soda, salt, and cinnamon until well combined.
Mix Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Add Oats, Raisins, and Nuts: Stir in the oats, raisins, and chopped nuts (if using) until evenly distributed in the dough.
Scoop the Dough: Using a cookie scoop or two teaspoons, drop rounded tablespoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake the Cookies: Bake the cookies in the preheated oven for about 10-12 minutes, or until the edges are lightly golden and the centers are set. If you like soft and chewy cookies, err on the side of slightly underbaking them.
Cool the Cookies: Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
