Line 2 baking sheets with parchment paper. Set aside.
In a large skillet, melt butter over medium heat. Add 2 tablespoons flour; cook 2 minutes, stirring until smooth. Gradually add milk and 4 cups Cheddar, stirring to combine. Cook, stirring constantly, until cheese melts and mixture is smooth. Remove from heat. Add cooked pasta, stirring to combine.
In a large bowl, combine remaining 2 cups Cheddar, 2 cups bread crumbs, 2 tablespoons flour, Parmesan, and 1⁄8 teaspoon red pepper. Fold in beaten egg whites. Add egg-white mixture to macaroni mixture, stirring to combine. Shape into 11⁄2-inch balls, and place on prepared pans. Freeze 15 minutes.
In a medium Dutch oven, add oil to halfway full. Heat over medium-high heat until a deep-fry thermometer reads 350°.
In a shallow bowl, place remaining 4 cups bread crumbs. In another shallow bowl, combine remaining 4 cups flour, salt, and remaining 1⁄8 teaspoon red pepper. In a third shallow bowl, place eggs. Roll macaroni balls in flour mixture. Dip in egg; dredge in bread crumbs.
Cook macaroni balls in batches until golden brown, 3 to 5 minutes, turning as needed. Let drain on paper towels. Serve immediately.
Recipe by Southern Cast Iron at https://www.southerncastiron.com/fried-macaroni-cheese-balls/