Bring 5 quarts of water to a boil in a large pot over high heat. Add the salt. Add the macaroni and cook, stirring occasionally for 2 minutes less than the time recommended on the package (the pasta will continue to cook in the Traeger). Drain the macaroni well, then transfer to a large bowl.

Melt 8 tablespoons of butter in a medium saucepan over medium heat. Gradually add the flour and dry mustard, whisking constantly. Continue whisking for about 2 minutes, but do not let the mixture brown. Gradually whisk in the milk, whisking continuously until the sauce is smooth.

Reduce the heat to medium-low and stir in the Velveeta, one-third at a time, until fully incorporated and melted, adding more milk if the sauce seems too thick; it should fall off the whisk in ribbons. Season with salt and pepper to taste.

Pour the cheese sauce over the pasta and stir gently with a rubber spatula or wooden spoon until fully coated.

Grease a roasting pan or casserole dish with butter, then pour the macaroni and cheese into the pan and spread evenly. Sprinkle the cheddar cheese on top.

Melt the remaining 4 tablespoons of butter in a medium saucepan. Add the bread crumbs and stir to coat.

Sprinkle the bread crumbs evenly over the macaroni and cheese and dust lightly with paprika.

When ready to cook, set the Traeger temperature to 350℉ and preheat with the lid closed for 15 minutes.

Transfer the roasting pan to the grill, close the lid, and bake the macaroni and cheese, rotating 180° halfway through, until hot and bubbling and the bread crumbs are golden brown, 45-60 minutes.

Remove the pan from the grill and serve hot. Enjoy!