2 cups (8 ounces) elbow macaroni
1/4 cup (1/2 stick) unsalted butter, cut into small pieces
One 12-ounce can evaporated milk
3 cups extra-sharp cheddar, shredded (12 ounces)
2 large eggs, lightly beaten
1 teaspoon dry mustard dissolved in 1 teaspoon hot water
1/2 teaspoon salt, or to taste
1/4 teaspoon ground red pepper, or to taste
Cook the macaroni in a large pot of boiling salted water. Drain and return to the pot.
Add butter. Stir until well blended. Add and stir well the evaporated milk, cheddar, eggs, mustard, salt, and pepper. Set the pot over very low heat and cook, stir constantly, until the sauce is smooth and the pasta is steaming, 5 to 10 minutes. The sauce should thicken noticeably.
Increase the heat slightly if the sauce is still soupy after 5 minutes, but watch it very carefully. Do not overheat, or the sauce will curdle.