Step 1

Line a rimmed baking sheet with parchment paper.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugars at medium speed until fluffy, 2 to 3 minutes, stopping to scrape the sides of the bowl. Add the egg and egg yolk, one at a time, beating well after each addition. Beat in the vanilla bean paste.

Step 3

In a medium bowl, whisk together the flour, black cocoa, baking powder, salt, and baking soda. With the mixer on low speed, gradually add the flour mixture to the butter mixture, beating just until combined. Stir in the chopped chocolate.

Step 4

Using a 2 or 3 Tbsp (I used a 2 Tbsp) cookie scoop, scoop dough (about 40 grams each), and place on prepared pan. Cover and refrigerate for at least 2 hours or overnight.

Step 5

Preheat the oven to 350°f / 180°c. Line 4 baking sheets with parchment paper.

Step 6

Roll chilled dough balls into balls. Place at least 2 ½ inches apart on prepared pans - only place as many dough balls as you are going to bake in one go on the pans, leave the rest in the fridge until ready to bake.

Step 7

For a soft center, bake for 10 to 12 minutes. For a crispy cookie, bake for 14 minutes. Rotate pans half way through baking. Let cool on pans for 5 minutes. Remove from pans, and let cool completely on wire racks. Serve warm or at room temperature.