Preheat oven to 350°F (175°C).
Line a baking sheet or loaf pan with parchment paper or lightly grease.
Mix in a large bowl:
2 lb (900 g) ground beef
1 cup breadcrumbs
1/2 cup milk
1 small onion, finely chopped (or 1/2 cup)
2 cloves garlic, minced
2 eggs
2 tsp Worcestershire sauce
1 tsp salt
1/2 tsp black pepper
1 tsp smoked paprika (optional)
1/2 cup chopped parsley (optional)
Add 1/2 cup ketchup (or barbecue sauce) to the mixture (optional).
Mix until just combined; avoid overmixing.
Shape into a loaf in a loaf pan or on the lined baking sheet.
Stir together glaze:
1/2 cup ketchup
2 tbsp brown sugar (or honey)
1 tbsp vinegar or lemon juice (optional)
1 tsp mustard (optional)
1–2 tsp Worcestershire sauce (optional)
Spread glaze over the top of the loaf.
Bake 50–70 minutes, until the center reaches 160°F (71°C).
Rest 10 minutes before slicing.