Bake for 7 minutes or just until set on convection, or 8-10 minutes on regular bake.
Remove from oven and let cool.
Make frosting:
Cream 1/4 cup butter, 1/4 cup Nutella, 2 tablespoons unsweetened cocoa and powdered sugar until smooth.
Add milk if necessary to spread consistency. Beat for 2 minutes until light and fluffy.
Before frosting cooled cookies, mix frosting with a spatula to remove any air bubbles.
Top cookies with prepared frosting or simply spread with additional Nutella out of the jar.
Notes
-*microwaving the butter will help the butter to blend better with the sugars. Do not overheat the butter. It should still be firm to the touch. You should be able to make an indent with your finger if applying pressure to the butter, without having the cube of butter collapse. Alternatively, you may remove the butter from the refrigerator about 30-45 minutes before making cookies. -The eggs should be cold when adding to the dough mixture. -Do not refrigerate the Nutella. It should be stored at rom temperature, similar to peanut butter, even after opening the container. -If you have a convection oven, make sure to use the convection setting to bake cookies. If you do not, you can refrigerate the dough before baking to help the cookies hold their shape. After shaping the cookies and placing on cookie sheets, place the sheet in the refrigerator for at least 30 minutes. When the dough is cold, bake at 375 for 10 minutes or until the dough is set and does not appear to be wet on top. You may also add an additional 2 tablespoons of flour to the dough if you do not have a convection oven this will also help the cookies hold their shape while baking. Bake the cookies as directed at 375 for about 10 minutes.