Preheat your oven to 350°F (175°C).

In a large skillet over medium heat, cook the bacon until crispy. Remove and set aside, keeping some bacon grease in the skillet.

In the same skillet, sauté diced onion and minced garlic until fragrant, then add ground beef and cook until browned. Season with salt and pepper.

In a large mixing bowl, combine the cooked beef mixture with crumbled bacon, cheddar cheese, Monterey Jack cheese, eggs, and milk. Stir until well incorporated.

Transfer the mixture into a greased baking dish and spread evenly. Bake for about 30 minutes or until set and bubbly.

Let the casserole sit for about 10 minutes before slicing.

Garnish with freshly chopped parsley before serving warm.