Preheat your oven to 350°F (175°C). This ensures that your cookies will bake evenly.
Cream together 1 cup of softened unsalted butter, 3/4 cup brown sugar, and 3/4 cup granulated sugar until smooth. This step is essential for achieving a light and fluffy texture.
Beat in 2 large eggs one at a time, followed by 1 tsp of peppermint extract. Mixing in the eggs one at a time helps to incorporate air and keeps the batter from becoming too dense.
In another bowl, whisk together 2 1/4 cups all-purpose flour, 1 tsp baking soda, and 1/2 tsp salt. This allows the leavening agents to distribute evenly throughout the flour.
Gradually mix the dry ingredients into the wet mixture until combined. Be careful not to overmix, as this can make the cookies tough.
Fold in 1 cup of mint chocolate chunks and nuts if you're using 1/2 cup chopped walnuts or pecans. This step adds texture and flavor to each cookie.
Drop spoonfuls of dough onto ungreased baking sheets, spacing them about 2 inches apart. This allows room for the cookies to spread as they bake.
Bake for 10-12 minutes, or until the edges are golden. Keep an eye on them; perfect baking time may vary based on your oven.
Allow the cookies to cool for a few minutes before transferring them to a wire rack. This makes for easier handling and ensures they don’t break apart.