01 - Preheat oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the flour, baking soda, salt, and ground cinnamon until evenly blended. Set aside.
03 - In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar together using an electric mixer on medium speed until pale, light, and fluffy, about 2 to 3 minutes.
04 - Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract until fully combined.
05 - Gradually add the dry ingredient mixture to the creamed butter mixture, mixing on low speed until just combined. Avoid overmixing to keep the cookies tender.
06 - Using a spatula, gently fold in the rolled oats, raisins, diced apple, and chopped nuts if using, until evenly distributed throughout the dough.
07 - Drop rounded tablespoons of dough onto the prepared baking sheets, spacing them approximately 2 inches apart to allow for spreading.
08 - Bake for 11 to 13 minutes, or until the edges are golden and the centers appear slightly underbaked. This ensures a soft, chewy texture.
09 - Let the cookies rest on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely before serving or storing.