Step 1: Boil the Pasta
Bring a large pot of salted water to a boil.
Add the elbow macaroni and cook until just al dente (do not overcook, as it will continue to soften in the sauce).
Drain the pasta completely, but do not rinse it.
Step 2: Create the Egg & Evaporated Milk Mixture
While the pasta is boiling, whisk together the evaporated milk, two large eggs, dry mustard, and smoked paprika in a medium bowl until completely smooth.
Step 3: Combine and Melt (Stovetop Method)
Return the hot, drained pasta back into the warm cooking pot.
Stir in the 4 tablespoons of cubed butter until it is fully melted and coats the macaroni.
Pour the egg and evaporated milk mixture directly over the warm pasta.
Turn the burner to the lowest possible heat setting.
Gradually add your freshly grated cheese in small handfuls, stirring constantly.
Pro Tip: As soon as the cheese is fully melted and glossy, remove the pot from the heat immediately to prevent the sauce from separating or getting grainy.
Step 4: The Baked Finish (Optional)
If you prefer the classic baked finish, preheat your oven to 350°F (177°C).
Transfer your prepared stovetop mac and cheese into a greased 2-quart baking dish.
Toss the panko breadcrumbs with 1 tablespoon of melted butter and scatter them evenly over the top.
Bake at 350°F for 25 to 30 minutes until the edges are bubbling and the crust is beautifully golden-brown.
Check the center with a thermometer to ensure it hits the safe internal temp of 160°F. Let it rest for 10 minutes before serving.