Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish and set it aside.
In a large skillet set over medium heat, sauté the chopped bacon until it becomes crisp. Transfer the cooked bacon to a plate lined with paper towels, reserving about 1 tablespoon of the rendered fat in the skillet.
Add the ground beef and minced onion to the same pan. Cook for 6–8 minutes, stirring occasionally, until the beef is browned and the onion is soft and translucent. Carefully drain any excess fat.
Stir in the minced garlic, Worcestershire sauce, salt, pepper, mustard, ketchup, and mayonnaise. Mix thoroughly to combine all ingredients evenly, then remove the skillet from the heat.
Incorporate half of the shredded cheddar, the full amount of shredded mozzarella, the reserved bacon, and the cooked pasta into the meat mixture. Stir until the pasta and beef are fully coated with the sauce and cheese.
In a separate small bowl, whisk together the eggs and cream (or milk) until smooth. Pour this mixture into the skillet and fold it into the pasta-beef blend until evenly distributed.
Transfer the entire mixture into the prepared baking dish. Sprinkle the remaining cheddar cheese evenly over the top.
Bake for 20–25 minutes, or until the top is golden and the casserole is bubbling at the edges.
Allow the casserole to cool for about 5 minutes before serving. Garnish with your choice of sliced pickles, diced tomatoes, or green onions if desired.