Preheat the oven to 425 degrees. Evenly grease each cup of a nonstick 12-cup muffin tin with butter. Press the breadcrumbs on the bottoms and up the sides. Set aside.
Cut the potatoes in half lengthwise, cut each half into 3 wedges and cut each wedge into ¼-inch slices. Place the potatoes, half-and-half, salt and pepper in a large glass bowl. Cover, microwave for 6 minutes and stir. Microwave another 6 to 8 minutes or until the potatoes are tender when tested with a toothpick or cake tester.
Meanwhile, in a separate bowl mix together the cheddar, Parmesan-Reggiano and cornstarch. Reserve ½ cup and set aside. Stir the cheese mixture into the potatoes, mixing gently until smooth.
Divide the potato mixture evenly among the muffin cups. Sprinkle each top with the reserved cheese mixture. Cover with aluminum foil that has been sprayed with cooking spray. Bake on the bottom rack for 10 minutes. Remove from the oven and uncover. Return to the oven and bake 13 to 14 minutes or until golden-brown.
Remove from the oven and immediately run a knife around the edge of each muffin cup. Allow to cool in the pan on a wire rack for 5 minutes. Place a baking sheet over the muffin pan and invert the potato cups, tapping the bottoms of the cups if necessary to fully release. Invert again onto the wire rack to cool another 5 minutes before serving warm.
Recipe by The Tennessee Magazine at https://www.tnmagazine.org/parmesan-reggiano/