Heat oven to 350 degrees. In a medium bowl, beat the brownie mix, butter, cream cheese, and egg. The dough will be a little sticky but very thick. Scoop the dough onto an ungreased cookie sheet, making 24 cookies. Smooth the edges of each to form a round cookie.
Bake for the cookie dough 12 minutes at 350 degrees, keeping an eye out to make sure the cookies don't over cook or under cook.
While the cookies are baking, prepare the Nutella filling. Combine together the Nutella, powdered sugar and heavy cream. The mixture will be very thick. Be sure that all of the powdered sugar gets mixed in. Add more cream as necessary. 3 tablespoons was all we needed.
Roll the Nutella mixture into 24 balls. Cover the balls with plastic wrap while the cookies finish baking.
As soon as the cookies come out of the oven, press a Nutella dough ball lightly into the center of each cookie. Let the cookies cool for 5 minutes, then transfer them to a wire rack to cool completely.
Melt the chocolate a microwaveable bowl for 30 seconds. Stir the chocolate and melt for additional 15 seconds or until the chocolate is completely melted. Spoon about 1/2 a tablespoon of melted chocolate on top of each cookie so it covers the cookie dough ball.
Let the chocolate set. Store in an airtight container.
The calories shown are based on the recipe making 24 cookies, with 1 serving being 1 cookie. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.