Preheat the oven: Preheat your oven to 375°F (190°C). Lightly grease a loaf pan or line a baking sheet with parchment paper.
Prepare the mixture: In a large bowl, combine the ground beef, onion, eggs, breadcrumbs, milk, garlic, Worcestershire sauce, salt, pepper, and Italian seasoning.
Mix gently: Use your hands or a large spoon to combine everything just until evenly mixed. Avoid overmixing so the meatloaf stays tender.
Shape the meatloaf: Transfer the mixture to the prepared pan and shape it into an even loaf.
Make the glaze: In a small bowl, mix together the ketchup, brown sugar, and mustard.
Add the glaze: Spread about half of the glaze evenly over the top of the meatloaf.
Bake: Bake for 45 minutes. Spread the remaining glaze over the top and continue baking for another 15–20 minutes, or until the center reaches 160°F (71°C).
Rest: Remove from the oven and let the meatloaf rest for 10 minutes before slicing.
Serve: Slice and serve warm with mashed potatoes, green beans, or your favorite sides.