Preheat your oven to 350°F (175°C).

In a large skillet, melt the butter over medium heat. Add the chopped onions and cook until softened and translucent, about 5 minutes. Remove from heat and let cool slightly.

In a large mixing bowl, combine the ground beef, beaten eggs, cooked onions, tomato sauce, crushed saltines, grated Cheddar cheese, Worcestershire sauce, salt, black pepper, and ketchup. Mix gently until all ingredients are evenly incorporated, being careful not to overwork the meat.

Transfer the meat mixture to a loaf pan or shape it into a loaf on a baking sheet lined with parchment paper.

Bake for about 1 hour or until the internal temperature reaches 160°F (71°C) and the meatloaf is cooked through.

Let the meatloaf rest for 10 minutes before slicing. Serve warm with your favorite sides.