Preheat the oven to 350°F.
Microwave the butter for about 40 seconds until it is almost fully melted. It should not be hot.
In a stand mixer or with electric beaters, beat the melted butter, white sugar, and brown sugar until creamy.
Add the vanilla and egg. Beat on low speed for 10 to 15 seconds, just until combined.
Add the flour, baking soda, and salt. Mix until crumbs form.
Use your hands to press the mixture together into a dough ball. The dough should be soft and easy to handle.
Fold in the chocolate chips and chocolate chunks, if using.
Roll the dough into 12 large balls, or 9 extra-large balls for bakery-style cookies.
Place on a baking sheet and bake for 9 to 11 minutes. The Soft Chocolate Chip Cookies should look puffy, pale, and just barely golden.
Do not overbake. Remove from the oven even if they look slightly underdone.
Let the cookies cool on the baking sheet for about 30 minutes. They will settle into soft, dense, buttery cookies.