First, cook the bacon until crispy. You can bake it on a sheet pan in the oven or cook it on the stovetop. Drain on paper towels, then chop into small pieces and set aside.

Prepare the macaroni according to the package instructions, then drain and set aside.

While the macaroni is cooking, brown the ground beef in a large skillet until fully cooked. If there's excess fat or liquid, drain some of it off. Keeping a bit of the juice enhances the flavor.

In a small bowl or measuring jug, combine the beef stock, Worcestershire sauce, ketchup, and cornstarch. Mix well to dissolve the cornstarch completely.

Add the cooked pasta to the skillet with the browned beef. Pour in the beef stock mixture and stir to combine thoroughly. Mix in the chopped bacon.

Cook over medium heat until the sauce starts to bubble and thicken. If the sauce is too thick, add a little more beef stock to reach your desired consistency.

Sprinkle the shredded cheddar and mozzarella cheeses over the top of the casserole mixture in the skillet.

Cover the skillet and cook on very low heat until the cheese melts, about 2-3 minutes.

Serve the casserole hot and enjoy!