Preheat Oven: Preheat your oven to 350°F (175°C).

Cook the Pasta: In a large pot, cook the elbow macaroni according to package instructions until al dente. Drain and set aside.

Cook the Bacon: In a large skillet over medium heat, cook the chopped bacon until crispy. Remove the bacon and drain on paper towels, leaving about 1 tablespoon of bacon grease in the skillet.

Cook the Beef: In the same skillet, add the ground beef and cook until browned. Add the chopped onion and minced garlic, cooking until the onion is translucent, about 3-4 minutes. Drain excess grease if necessary.

Make the Cheese Sauce: In a large bowl, combine the cooked macaroni, cooked bacon, beef mixture, milk, beef broth, Worcestershire sauce, mustard, and half of the cheddar and mozzarella cheeses. Mix well and season with salt and black pepper.

Transfer to Baking Dish: Pour the mac and cheese mixture into a greased 9x13-inch baking dish. Sprinkle the remaining cheddar and mozzarella cheeses on top.

Add Breadcrumbs (Optional): If using, mix the breadcrumbs with olive oil and sprinkle over the cheese layer for added crunch.

Bake: Bake in the preheated oven for 25-30 minutes, or until the cheese is bubbly and golden.

Serve: Remove from the oven and let it cool for a few minutes. Garnish with chopped green onions if desired.