2 cups chocholate chips (or chunks, or chopped chocolate)
Place the melted butter in the bowl of a stand mixer fitted with the paddle attachment (or large bowl if using a hand mixer). Add granulated and brown sugars and mix it on low speed until the mixture is smooth. Mix it in egg and vanilla extract and mix on medium speed until combined.
Mix it in baking soda and salt, then slowly mix in the flour and mix just until the batter is smooth and comes together. Be sure to scrape the sides of the bowl during mixing. Slowly mix it in chocolate chips.
Line a cookie sheet with a silicone baking mat or parchment paper. Scoop 2 tbsp balls of dough onto the cookie sheet. Spacing does not matter because you will be chilling the dough. Cover it with plastic wrap and chill for at least 2 hours.
Preheat oven to 350°F. Line a second cookie sheet with parchment paper or a silicone baking mat.
Remove the chilled cookie dough balls from the refrigerator and space them 2-inches apart on the cookie sheets. Bake it (2 tbsp sized cookies) for 11-15 min, or until the edges are light golden and the tops are no longer glossy. cool on the cookie sheets at least 10 min before removing.