In a large skillet over medium heat, add chopped bacon and sauté for about 7-10 minutes until crispy and golden. Transfer to a paper towel-lined plate to drain excess grease.

In the same skillet, leave about a tablespoon of rendered bacon fat, then add diced onion and minced garlic. Sauté for 3-4 minutes until the onion is translucent. Stir in ground beef, cooking until browned for 5-6 minutes. Drain excess fat and mix in tomato sauce, cooking for another 2-3 minutes until heated through.

Bring a large pot of salted water to a boil and add the lasagna noodles. Cook for approximately 8-10 minutes until al dente according to package instructions. Drain and lay the noodles flat.

In a medium saucepan over medium heat, melt 4 tablespoons of butter. Whisk in 1/4 cup of flour and stir for 1-2 minutes until bubbly. Gradually whisk in 2 cups of milk and cook until thickened, about 5 minutes. Remove from heat and stir in grated Parmesan and shredded mozzarella until melted and creamy.

Assemble the lasagna by spreading a thin layer of meat sauce at the bottom of a 9x13-inch baking dish. Add a layer of lasagna noodles, then a layer of cheese sauce, followed by crispy bacon. Repeat, finishing with cheese sauce and additional grated Parmesan on top.

Preheat oven to 375°F (190°C). Cover tightly with aluminum foil and bake for 30 minutes. Remove foil and bake for another 10-15 minutes until golden and bubbly.

Allow the lasagna to rest for about 10 minutes before slicing. Garnish with fresh herbs like parsley or basil before serving.