Line a small baking pan or large plate with parchment paper and set aside.
In a medium bowl, add slightly melted butter, brown sugar, and granulated sugar and mix using a spatula. Then add the egg and vanilla extract and mix until completely combined.
½ cup (113 g) salted butter, ¾ cup (150 g) dark brown sugar, ¼ cup (50 g) granulated sugar, 1 large egg, 2 tsp vanilla extract
Add the flour, baking soda, salt, and chocolates and mix until JUST incorporated. Do not over mix.
1½ cups (180 g) all purpose flour, ½ tsp baking soda, 6 oz. (170 g) dark chocolate chunks, chopped, 2 oz. (56 g) milk chocolate chunks, chopped, ¼-½ tsp salt
Divide the dough into 8 balls (see notes), add remaining chocolate chunks on top, then place in the parchment lined pan/plate. Cover and refrigerate for at least 12 hours, preferably 24-72 hours. My favorite is to chill for 48 hours.
Preheat the oven to 350℉ and line a baking sheet with parchment paper.
Place chilled dough on the baking sheet. For a large baking sheet, I like to add no more than 5.
Bake for 12-14 minutes. Remove from oven and let cool for 5 minutes before transferring to wire rack to cool completely. If making them smaller, bake them for 10-12 minutes. To get beautiful ripples in your cookies, bang the pan a few times right when you take it out of the oven. This will deflate the cookies, cause beautiful ripples, and create crispy edges and chewy centers.
TIP: To create perfectly round cookies, use the cookie cutter method: place the large cutter over the cookies and create small round motions. Make sure the cookie cutter is much larger than the cookie. You can even use a glass or a round bowl.
Cookies will last at room temperature in an airtight container for 3-4 days.