Instructions:
- Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
- In a medium bowl, whisk together the flour, oats, baking soda, cinnamon, nutmeg, and salt. Set aside.
- In a large bowl or stand mixer, beat the softened butter, brown sugar, and granulated sugar together on medium speed until light and fluffy (about 3 minutes).
- Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract. Scrape down the sides of the bowl.
- Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed just until combined. Do not overmix.
- Gently fold in the raisins or cranberries (if using) using a spatula.
- For best results, cover the dough and chill for 15 minutes to help prevent excessive spreading.
- Drop rounded tablespoons of dough onto the prepared sheets, spacing them 2 inches apart. Lightly press the tops of the dough balls down slightly with your fingers.
- Bake for 10–12 minutes, rotating the sheets halfway through. Cookies are done when the edges are golden brown but the centers still look slightly soft.
- Let cookies cool on the baking sheet for 5 minutes before transferring them carefully to a wire rack to cool completely.