Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish. Gather all your ingredients and have them measured and ready.
Step 2: In a large skillet over medium-high heat, brown the ground beef along with the chopped onion, breaking up the beef. Cook until no longer pink and onion is softened (5-7 minutes). Drain excess grease thoroughly. Stir in minced garlic and cook for 1 minute until fragrant.
Step 3: Reduce heat and stir in condensed cream of mushroom soup, milk, ketchup, yellow mustard, Worcestershire sauce, salt, and black pepper into the ground beef mixture. Stir until combined and gently simmering. Remove from heat. Stir in half of the crumbled crispy bacon and 1 cup of shredded cheddar cheese.
Step 4: Unroll the can of refrigerated crescent roll dough and press it into the bottom of the prepared 9x13-inch baking dish, pinching together all seams to form a solid crust.
Step 5: Spread the savory ground beef mixture evenly over the crescent roll crust. Top with the remaining 1 cup of shredded cheddar cheese, followed by the 1 cup of shredded Monterey Jack cheese. Scatter the remaining crumbled bacon over the cheesy layer.
Step 6: Place the assembled casserole into your preheated oven and bake for 25-30 minutes, until cheese is melted, gloriously bubbly, and the crescent roll crust has turned a beautiful golden brown around the edges. Let stand for 5-10 minutes before slicing and serving. Garnish with any optional toppings.