Step 1

In a large bowl, beat the softened butter and sugars with an electric mixer on medium speed until light and fluffy, about 3 minutes. Turn the mixer to low and blend in the egg, yolk, and vanilla extract, mixing until well combined.

Step 2

In a separate bowl, whisk the flour, cocoa powder, baking soda, and salt. Add the dry to the wet ingredients and mix gently by hand with a spatula or wooden spoon until about halfway combined. Add 1 cup of chocolate chips and mix until no streaks of flour are visible.

Step 3

Cover the bowl and chill the dough for at least three hours (or up to 3 days).

Step 4

Preheat the oven to 350°F. Line large baking sheets with parchment paper.

Step 5

Let the dough sit at room temperature for 10-15 minutes. Then, portion it into 1 1/2 tablespoon balls and arrange on the baking sheets with 2-3 inches between each. You should get about 20.

Step 6

Bake for 10-12 minutes, until the edges look set and the centers are still soft.

Step 7

Immediately after removing the trays from the oven, carefully press the extra chocolate chips into the tops of the cookies.

Step 8

Cool on the baking sheets for 5-10 minutes before transferring to a wire rack to cool fully. Enjoy!