01 - Cook the elbow macaroni in salted boiling water according to package directions. Drain thoroughly and set aside.
02 - Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1 minute, stirring constantly to form a smooth paste.
03 - Gradually whisk in milk, stirring constantly to prevent lumps. Cook until the sauce slightly thickens, about 2-3 minutes. Reduce heat to low.
04 - Add sharp cheddar, mozzarella, salt, pepper, and paprika. Stir continuously until all cheese is melted and the sauce is smooth and creamy.
05 - Pour the drained macaroni into the cheese sauce. Mix thoroughly to ensure every piece is evenly coated.
06 - Spread the mixture evenly on a parchment-lined baking sheet. Cover and refrigerate until firm, at least 2 hours. Alternatively, freeze for 30 minutes.
07 - Scoop heaping tablespoons of the chilled macaroni mixture and roll into 1.5-inch balls with your hands.
08 - Prepare three shallow bowls: whisk eggs with 2 tbsp milk in the first, place flour in the second, and breadcrumbs in the third.
09 - Dredge each ball in flour, shake off excess, dip into egg mixture, then press firmly into breadcrumbs to coat completely. Place on a tray.
10 - Pour vegetable oil into a deep pot to a depth of 2 inches. Heat to 350°F, using a thermometer to ensure proper temperature.
11 - Fry balls in batches of 4-6, turning occasionally, until golden brown and crispy, about 2-3 minutes per batch. Remove with a slotted spoon.
12 - Transfer fried balls to paper towels to drain excess oil. Serve immediately with warm marinara sauce and garnish with chopped parsley if desired.