Prep. Preheat oven to 375 degrees. Spray a 9X13 inch baking dish with nonstick cooking spray; set aside.
    Beef. In a large pot, cook the ground beef, sprinkle with salt and pepper, and cook, crumbling with a wooden spoon until no pink remains in the beef. Remove cooked beef to a paper towel-lined plate.
    Veggies. Drain all but 2 tablespoons of the fat from the pan and set over low heat (if you don't have enough fat in the pan, add a tablespoon of vegetable oil). Add onions, green pepper, and garlic to the skillet. Saute over medium heat until veggies are soft. Add cooked beef back to the skillet.
    Sauce. Stir in dark brown sugar, apple cider vinegar, Worcestershire sauce, dry mustard, both cans of tomato sauce, ketchup, and beef broth, and mix until well combined. Simmer until thickened, 5 to 10 minutes.
    Pasta. Meanwhile, cook the pasta in a large pot of salted boiling water according to package instructions, just until al dente. Drain and add to the meat sauce. Stir until evenly combined.
    Assemble + bake. Transfer pasta and meat mixture to prepared baking dish. Top evenly with cheese. Bake in preheated oven for 20 minutes. Garnish with chopped parsley and serve.