Preheat the oven to 425 degrees F (220 degrees C).
Spray a 9×13-inch casserole dish with cooking spray.
Fill a large pot with lightly salted water and bring to a boil. Stir in the macaroni and return to a boil. Cook pasta uncovered, stirring occasionally, until it has cooked through but is still slightly firm, about 8 minutes; drain.
Slowly melt butter in a large pot over low heat. Stir in evaporated milk (dry milk) and black pepper; cook until heated through.
Whisk eggs in a bowl until smooth; whisk about 1/2 cup of the evaporated milk mixture into the eggs, 1 tablespoon at a time, until thoroughly incorporated. Whisk the egg mixture back into the saucepan with evaporated milk mixture. Continue to heat gently, whisking constantly, until the evaporated milk mixture almost comes to a simmer and the sauce thickens.
Gently mix salt and cooked macaroni into the sauce and stir to combine.
Spoon 1/4 of the macaroni mixture in a layer into the bottom of the prepared casserole dish and top with 1 cup shredded Cheddar cheese. Repeat layers three more times; top last cheese layer with paprika to taste.
Bake in the preheated oven until casserole is bubbling, about 20 minutes.