Preheat your oven to 400°F (200°C) and line two baking sheets with parchment paper.

Cream 1 cup of softened unsalted butter with 3/4 cup of light brown sugar and 3/4 cup of granulated sugar until light and fluffy.

Add 2 large eggs one at a time, then stir in 2 teaspoons of vanilla extract until smooth.

Whisk together 2 1/4 cups of all-purpose flour, 1 teaspoon of baking soda, and 1/2 teaspoon of salt.

Gradually mix the dry ingredients into the wet mixture until just combined.

Fold in 1 cup each of semi-sweet and milk chocolate chunks, and 1 cup of chopped walnuts if using.

Scoop large portions of dough (about 6 ounces each) onto the prepared baking sheets, spacing them 2-3 inches apart.

Bake for 13-15 minutes until the edges are golden and the centers are slightly underbaked.

Allow the cookies to cool on the baking sheets for at least 10 minutes before transferring to a wire rack.