Heat 1 teaspoon of olive oil in your skillet over medium heat. Add the diced onion and cook until softened and translucent, about 5 minutes. Stir in the minced garlic and cook for an additional 1 minute until fragrant. Remove from heat and let cool slightly.
In a large mixing bowl, combine the lean ground beef, breadcrumbs, milk, half of the ketchup (about 2 tablespoons), Worcestershire sauce, beaten egg, salt, and pepper. Add the sautéed onions and garlic. Mix gently until just combined, avoiding overmixing to keep the meatloaf tender.
Lightly grease your loaf pan or baking dish. Spread half of the meat mixture evenly into the bottom of the pan, pressing down gently. Sprinkle the cubed sharp cheddar cheese evenly over this layer. Then, cover with the remaining meat mixture and smooth the top.
Spread the remaining ketchup over the top of the meatloaf. Place the meatloaf in a preheated oven at 350°F (175°C) and bake for 50-60 minutes, or until the internal temperature reaches 160°F (71°C).
Once out of the oven, let the meatloaf rest for 10 minutes before slicing. Serve with your favorite sides like creamy mashed potatoes or fresh green vegetables.
