In a food processor, blend the almond flour, coffee, and powdered sugar until very finely ground, then set aside.
With a mixer fitted with a whisk, beat the egg whites until foamy, then slowly begin to add the granulated sugar until you have created a glossy meringue.
Add the almond mixture to the meringues all at once, and quickly fold to blend and break up some of the air.
Continue to slowly mix until the almonds are incorporated into the meringues.
Once you have the right consistency, fill a pastry bag with a plain tip with the mixture, and carefully pipe circles of about 1.5 inches in diameter about 2 inches apart onto parchment paper.
Once you have completed piping allow the macarons to rest at room temperature for about 30 minutes to an hour to develop a skin. (You can tell if this has happened by lightly touching the top with your finger. If the mixture does not stick to your finger they are ready for baking.)
Preheat the CONVECTION oven to 265 degrees and carefully slide the parchment sheets onto a baking sheet and bake the macarons for 15 to 20 minutes depending on how large you piped them.
While baking they should rise with airy feet developing.
Once baked remove from the oven and cool for 10 minutes.
Carefully remove from the parchment using a small metal spatula.
Either pipe or spoon some of the Nutella onto one half of a macaron, and then top with another of equal size.