https://www.simplyrecipes.com/recipes/beef_chili_mac_and_cheese/
Ingredients
For the chili:

2 cups uncooked elbow pasta
1 tablespoon vegetable oil
1 yellow onion, diced
2 tomatoes, diced (or 1 15-oz can whole tomatoes, drained and diced)
1 pound ground beef
1 teaspoon freshly ground black pepper
1 tablespoon chili powder
1 tablespoon kosher salt
2 tablespoons unsalted butter
2 tablespoons all-purpose flour
2 cups whole milk
3 cups (12 ounces) shredded cheese, either a Mexican cheese blend (see Recipe Note) or cheddar
1 tablespoon yellow mustard
For the breadcrumbs:

2 tablespoons unsalted butter
1/2 teaspoon chili powder
1/4 teaspoon kosher salt
1/2 cup breadcrumbs