Chocolate sugar cookies are rich and fudgy, deeply chocolatey sugar cookies. These soft and chewy chocolate cookies are easy to make and are the perfect cookie for any gathering.
In a large mixing bowl, whisk in the cooled melted butter with the light brown and granulated sugars until well combined. Whisk in the egg, egg yolk, vanilla extract and cocoa powder until smooth and well combined.
Stir the dry ingredients into the wet until just combined. Cover the chocolate cookie dough and chill in the fridge while the oven preheats. The dough can remained covered in the fridge up to overnight.
Roll the dough into a ball. Roll the cookie dough ball into sugar and place the cookie dough balls onto the lined baking sheet about 3 inches (8 cm) apart. Bake the cocoa sugar cookies at 350 F (177 C) for 10 -12 minutes.