Bring a large pot of water to a boil. Add salt and macaroni, and cook until al dente. Drain and return to the pot.
Add Butter:
Stir in the butter until melted. Set aside.
Mix the Milk and Eggs:
In a large bowl, whisk together evaporated milk, milk, eggs, and garlic salt until fully combined.
Prepare the Cheese:
In a separate bowl, mix cheddar and mozzarella together.
Preheat Oven and Prepare Pan:
Preheat the oven to 375°F (190°C). Lightly spray a 9×13-inch baking dish.
Layer Macaroni and Cheese:
Place 1/3 of the macaroni in the baking dish.
Top with 1/3 of the cheese mixture.
Repeat twice more, ending with cheese.
Add Milk Mixture and Paprika:
Pour the milk and egg mixture evenly over the macaroni and cheese layers. Sprinkle paprika on top for color and flavor.
Bake:
Bake in the preheated oven for 25–30 minutes, until bubbly and golden on top.
