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.
11 ½ ounces milk chocolate chips, divided, ½ cup butter, sliced into tablespoons
Mix the dry ingredients together (flour, cocoa, baking soda, salt) in a bowl and set aside.
2 cups flour (250g), ⅓ cups unsweetened natural cocoa powder, 1 tsp baking soda, ¾ tsp fine sea salt
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.
2 eggs, ½ cup granulated sugar, ½ cup brown sugar, 2 tsp vanilla extract
Mix in the dry ingredients until just combined, then mix in the rest of the chocolate chips.
11 ½ ounces milk chocolate chips, divided
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.
Flaky sea salt