Chop the bacon into bite-sized pieces and cook in a large skillet over medium-high heat for 5 to 7 minutes until crispy, then remove with a slotted spoon and set aside, leaving about 2 tablespoons of bacon fat in the pan.

Add the ground beef to the skillet with the bacon fat and cook over medium-high heat for 5 to 7 minutes until browned, letting the beef sit undisturbed for 2 to 3 minutes to develop a crust before stirring.

Reduce heat to medium, add the diced onion and cook for 3 to 4 minutes until soft and translucent, then add the minced garlic and cook for 1 minute until fragrant.

Pour in the tomato sauce and diced tomatoes with their juice, then stir in the Worcestershire sauce, brown sugar, smoked paprika, garlic powder, black pepper, and salt until evenly combined.

Bring the sauce to a gentle simmer over medium heat, then reduce heat to low and let simmer for 10 to 12 minutes, stirring occasionally and adjusting seasoning as needed.

Meanwhile, bring a large pot of salted water to a boil and cook the spaghetti for 8 to 10 minutes until al dente, then reserve 1 cup of pasta water and drain the pasta without rinsing.

Return the drained pasta to the pot, pour the sauce over it, add the butter and reserved bacon, and toss over low heat for 2 minutes until the butter melts and the sauce coats the pasta, adding a splash of reserved pasta water if needed to loosen.

Serve the cowboy spaghetti hot, topped with grated Parmesan cheese and fresh parsley if desired.