See below

Boil 10 cups water, 1 tablespoon salt, 2 cups elbow pasta
Drain and return to pot with 4 tablespoon butter cut into small pieces, stir until well blended
Add: 12 ounces evaporated milk, 12 ounces extra sharp cheddar cheese, 2 eggs lightly beaten, 1 teaspoon mustard dissolved in 1 teaspoon water, 3/4 teaspoon salt, 1/2 teaspoon red pepper (optional)
Heat on medium for 5 to 10 minutes