Preheat the oven to 350°F and line a baking sheet with parchment paper.

Place ½ cup of chocolate chips and the butter in a heat-proof bowl set over a pot with 2 inches of simmering water, creating a double boiler. Stir the chocolate and butter constantly until fully melted. Set aside to cool slightly.

Mix the dry ingredients together (flour, cocoa, baking soda, salt) in a bowl and set aside.

Add the sugars, eggs, and vanilla to a separate, large bowl and mix together until incorporated. Add the melted chocolate and butter mixture and mix until smooth.

Mix in the dry ingredients until just combined, then mix in the rest of the chocolate chips.

Place the cookie dough in the fridge for 30 minutes to firm up slightly before baking.

Using a spoon or an ice cream scoop, form dough balls about 2 or 3 tbsp in size. Place 4 to 6 cookies on the baking sheet and bake for 9 to 11 minutes or until the edges look set and centers look just slightly soft.

Remove the tray from the oven and bang it onto the counter a couple times. This helps the cookies spread and flatten out, making them crinkly and chewy instead of cakey.

Sprinkle the cookies with flaky sea salt, then place them onto a cooking rack until ready to eat. Enjoy them warm or at room temperature.