1. Place diced potatoes in a pot and fill with enough cold water to cover. Add two tablespoons of salt and bring to a boil. Lower heat and simmer for an additional 20–25 minutes, until potatoes are tender.
2. While potatoes are cooking, sauté onion in one tablespoon of butter until soft and golden. Set aside.
3. Once the potatoes are tender, drain them and mash well. Stir in the remaining two tablespoons butter, sautéed onion, and cheeses while still hot, mixing well to incorporate. Add the beaten eggs, mixing quickly so the eggs don’t cook. Season with salt and pepper.
4. Spray 24 muffin cups lightly with cooking spray. Spoon mixture into muffin cups, smoothing out the tops of each with the back of a spoon. Divide mixture evenly among the cups and freeze for about one hour.
5. While the puffs are partially frozen, use an apple corer to punch a hole in the center of each “doughnut.” Return muffin pans to freezer and freeze for several hours or overnight.
6. Preheat oven to 350°F (175°C). Line two baking sheets with Gefen Parchment Paper and spray lightly with cooking spray.
7. Place cornflake crumbs in a medium-sized bowl. Add Italian seasoning and salt and mix well. Place eggs in another bowl and whisk until beaten. Dip frozen “doughnuts” into beaten egg and then into the crumbs, making sure to coat all sides well. Place on a baking sheet about two inches (five centimeters) apart. Bake for 30 minutes.
8. While the puffs are baking, prepare the sauce: Melt butter in a small saucepan. Add garlic and sauté over medium heat until lightly browned and fragrant. Add marinara sauce, heavy cream, and seasoning, and mix well to combine. Bring sauce to a low boil. Stir in Parmesan cheese and simmer for an additional four to five minutes until melted and fully incorporated.
9. To serve, spoon hot cream sauce over potato puffs and serve immediately.
