Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper or silicone baking mats.

In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar together using an electric mixer until smooth and creamy, about 3-4 minutes. This step helps create a soft and fluffy cookie base.

Beat in the eggs, one at a time, until fully incorporated. Then, mix in the vanilla extract. The eggs add moisture and richness to the cookies, while the vanilla enhances the flavor.

In a separate bowl, whisk together the flour, baking soda, cinnamon, and salt. Gradually add this dry mixture to the wet ingredients, mixing on low speed until just combined.

Using a spatula or wooden spoon, fold in the oats and raisins (and nuts, if using) until evenly distributed throughout the dough.

Use a cookie scoop or spoon to drop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches of space between each cookie to allow for spreading.

Bake for 10-12 minutes, or until the edges are golden brown but the centers are still slightly soft. This ensures a chewy texture.

Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely. Enjoy your oatmeal raisin cookies warm, with a glass of milk or your favorite tea!