Cook mac and cheese and cool until you can easily pick it up and form it.  Form mac and cheese into logs, roughly two inches long and about 3/4 inch thick.  Prepare two bowls, one with beaten egg and another with panko bread crumbs, salt and pepper mixed.

Option 1: Air Fryer (affiliate)

Place logs on parchment paper on a baking sheet and into freezer for 1-2 hours.  Preheat air fryer to 400°.  Remove and dip first into beaten egg, then into bread crumb mixture.  Roll around in each until fully covered.  Place in air fryer and repeat until all logs are dipped.  Cook for 15 minutes, shaking every few minutes.

Option 2: Pan Frying

Place logs in fridge for 30 minutes to hold shape.  Preheat vegetable oil in a medium pan until warm enough that it sizzles when logs are dipped.  Remove and dip first into egg mixture, then into panko bread crumbs.  Cook for 90 seconds on each side, then remove to a plate with paper towel.  Let cool two minutes before serving.

Option 3: Baked

Preheat oven to 425°.  Place mac and cheese logs into fridge for 30 minutes.  Remove from fridge and dip first into beaten egg before rolling in panko breadcrumb mixture.  Place on a lightly greased baking sheet and into center of preheated oven.  Bake for 20 minutes, flipping logs over halfway through.  Let cool a couple minutes before serving.