Preheat your oven to 350°F (175°C). Lightly grease a loaf pan or baking dish and set it aside.

In a small bowl, stir together the ketchup, brown sugar, and mustard until smooth. This is your sweet and tangy glaze. Set aside about two-thirds of the mixture for topping the meatloaf later. The remaining third will be mixed into the loaf itself for added moisture and flavor.

In a large mixing bowl, combine the ground sausage, ground beef, crushed crackers (or oats or breadcrumbs), chopped onion, eggs, salt, pepper, shredded cheese, and one-third of the prepared sauce. Using your hands or a sturdy spoon, mix gently until everything is just combined. Be careful not to overmix, as this can result in a dense meatloaf.

Transfer the meat mixture into the prepared pan or shape it into a loaf on a baking dish. Pat it into a firm, even log shape, approximately 8 inches long and 4 inches wide.

Bake uncovered for 1 hour. You’ll know it's getting close when your kitchen is filled with a rich, savory aroma.

After 60 minutes, remove the loaf from the oven and spoon or brush the remaining glaze over the top. Return the meatloaf to the oven and bake for an additional 10 minutes, allowing the glaze to bubble and caramelize slightly.

Use a meat thermometer to check the internal temperature—it should read 160°F (71°C) at the center. If you don't have a thermometer, the loaf should feel firm to the touch and the juices should run clear when sliced.

Let the meatloaf rest for 5 to 10 minutes before slicing. This helps lock in the juices and makes it easier to cut neat slices. Serve warm with classic sides like mashed potatoes, green beans, or cornbread.