Melt butter for 20 seconds in a small bowl or mug. Add in sugar, vanilla, egg yolk, Nutella, and flour. Mix with a fork until dough comes together. Dough might still be loose so you can use your hands to help thoroughly mix the dough and have the Nutella mixed in. Add in the chocolate chips and mix into the dough.
Shape the dough into shape of a cookie. Place on plate lined with parchment paper. Microwave for 50 seconds. Cookie will spread and should looked cooked but still delicate/breaks apart easily. Let cookie cool and firm up before eating.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.