Step 1: Preheat your oven to 350°F (175°C).
Step 2: In a large mixing bowl, combine the unsalted butter, light brown sugar, dark brown sugar, and granulated sugar. Beat on medium speed until light and fluffy, about 2-3 minutes.
Step 3: Add the eggs and vanilla extract to the mixture. Beat until fully incorporated.
Step 4: In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add to the wet ingredients, mixing on low speed until just combined.
Step 5: Fold in the semi-sweet chocolate chips and chopped walnuts or pecans.
Step 6: Scoop generous portions of dough onto a parchment-lined baking sheet, leaving space between each cookie.
Step 7: Bake for 12-15 minutes or until edges are lightly golden and centers are still soft.
Step 8: Cool on the baking sheet for 5 minutes before transferring to a cooling rack.
