Cook the pasta according to package directions. Drain and set aside.
In a medium saucepan (I used a 3 quart), melt butter over medium to medium-low heat. Once melted, add the flour and whisk constantly for about 3 minutes, until thickened and nutty. This is called a roux.
Gradually, add the milk, stirring until there are no lumps. Increase heat to medium and bring to a light simmer, whisking. It will thicken up.
Add the cheese and stir until melted and incorporated. Stir in the cooked pasta. Let cool and refrigerate in an airtight container for at least 4 hours or overnight.
Make the Mac and Cheese Bites
Form 1.5 inch balls with the cold mac and cheese, pressing to make them compact. Lay them on a sheet pan and put it back in the fridge while you prepare the rest of the ingredients. Note: they need to stay a bit cold (but not frozen) so they retain their shape well.
Prepare your breading station: In a shallow bowl, add the flour. Then, in a second shallow bowl, whisk the eggs. In a third shallow bowl, combine the panko bread crumbs, Italian bread crumbs, and 1 teaspoon salt. Set aside.
Get the oil ready: Heat the vegetable oil (3 to 4 inches deep, or enough for the mac and cheese bites to fully submerge) in a deep large Dutch oven until the oil’s temperature reaches 360 to 375 degrees F. Tip: Use a candy thermometer to measure the oil’s temperature.
While the oil is heating, assemble the mac and cheese bites: coat each ball in flour first, then the whisked eggs, and then the bread crumb mixture. Press slightly to make sure the bread crumbs adhere well.
Deep fry: Fry in small batches for about 3 minutes or until evenly golden brown. Tip: every time you add food into the oil, the temperature drops. Increase the heat to get it back closer to 360-375 degrees F.
Transfer to a large plate lined with paper towel to drain excess oil. Serve immediately. Enjoy!