In a medium bowl, sift the flour and cocoa powder. Then, add the salt and cornstarch and set aside.
1 cup All-purpose flour, ⅓ cup Unsweetened cocoa powder, 1 teaspoon Salt, 1 teaspoon Cornstarch
Melt the chocolate bars in a microwave safe bowl. Melt for 20 second intervals until melted. Make sure to stir well between each interval. Let it cool.
8 oz Semi-sweet chocolate bars
Using a mixer with a whisk attachment, beat the butter, brown sugar, and sugar on high for 2 minutes. Add the eggs and egg yolk. Beat on high for 3 minutes.
½ cup Unsalted butter, 1 cup Brown sugar, ⅓ cup White granulated sugar, 2 Large eggs, 1 Large egg yolk
If using a stand mixer, switch to a paddle attachment. Add the melted chocolate and vanilla. Mix on high speed until fully combined. Add in the dry ingredients and mix on low until just combined. Then, add in the chocolate chips.
2 teaspoon Pure vanilla extract, 1 ½ cups Semi-sweet chocolate chips
Preheat the oven to 350°F. Line two cookie sheets with parchment paper. Place the cookie dough in the fridge while the oven preheats. It needs to chill for 10-15 minutes.
Use a 2oz cookie scoop to scoop 6 cookie dough balls per cookie sheet. Top with extra chocolate chips.
Bake one cookie sheet at a time. Bake for 12-13 minutes until edges are baked and the middle.
Top the cookies with extra chocolate chips and a pinch of flaky sea salt. Let the cookies sit on the hot pan for 5 minutes before transferring to a cooling rack.
Flaky sea salt