Preheat oven to 350°F.
Line cookie sheet with parchment paper and set aside.
Cream butter, sugars, and Nutella together until smooth.
Add in eggs, additional egg yolk, cocoa powder and vanilla. Beat for about one minute on medium speed.
In a separate bowl, combine flour, baking soda, and salt.
Add dry ingredients to the wet ingredients a ½ cup at a time and mix until combined, scraping down the sides as needed.
Fold in chocolate chips
Roll into tbsp sized balls and place on prepared cookie sheet about two inches apart. If you want to, you can roll cookie dough in sprinkles before placing on pan, I did 50/50.
Bake for 10-12 minutes.
Cool on pan for a couple of minutes before transferring to a cooling rack.
Store in an air tight container with a piece of bread to keep them soft.