Preheat your oven to 375°F (190°C) and line two baking sheets with parchment paper.

In a mixing bowl, cream 1 cup of unsalted butter with 1 cup each of light or dark brown sugar and granulated sugar until light and fluffy.

Add 2 large eggs, one at a time, mixing well after each and then stir in 1 teaspoon of pure vanilla extract.

Whisk together 2.5 cups rolled oats, 2 cups all-purpose flour, 0.5 teaspoon kosher salt, 1 teaspoon baking powder, and 1 teaspoon baking soda in a separate bowl.

Gradually combine the dry mixture into the wet ingredients until just mixed.

Fold in 12 ounces of chocolate chips and optional chopped nuts.

Shape dough into 1 to 2-inch balls and place them 2 inches apart on the baking sheets.

Bake for 12 to 14 minutes until the edges are golden brown and centers are slightly soft.

Let cool on the baking sheet for 5 minutes before transferring to wire racks.