Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper. This temperature ensures perfect cookie spread and even baking.
Cream the butter and sugars together in a large bowl using an electric mixer on medium speed until light and fluffy, about 2-3 minutes. Don’t rush this step – proper creaming creates the foundation for perfect cookie texture.
Add the eggs one at a time, beating well after each addition, then mix in the vanilla extract until combined.
In a separate bowl, whisk together the flour, baking soda, cinnamon, and salt until evenly distributed.
Gradually add the dry ingredients to the wet mixture on low speed, mixing just until combined. Overmixing will develop gluten and make your cookies tough.
Fold in the oats, dried cranberries, and nuts (if using) with a wooden spoon or rubber spatula until evenly distributed throughout the dough.
Scoop rounded tablespoons of dough (about 2 tablespoons each) onto the prepared baking sheets, spacing them about 2 inches apart. The cookies will spread while baking.
Bake for 10-12 minutes or until the edges are golden but the centers still look slightly underdone. They’ll continue cooking on the hot baking sheet.
Allow the cookies to cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.