In a large skillet, heat 2 teaspoons of vegetable oil over medium-high heat. Add 1.5 pounds of ground beef, seasoning it with salt and pepper. Cook for 6-8 minutes, breaking the meat apart with a spatula until it's no longer pink.

Once the ground beef is browned, drain any excess grease carefully. Transfer the meat into a slow cooker, making sure to scrape the skillet.

To the slow cooker, add 16 ounces of tomato sauce, ½ cup of ketchup, 2 tablespoons of brown sugar, and 1 tablespoon of Worcestershire sauce. Stir in ½ teaspoon of garlic powder, ½ teaspoon of onion powder, 1 teaspoon of prepared mustard, and ½ teaspoon of smoked paprika.

Cover the slow cooker with its lid and set it to cook on HIGH for 3 hours or LOW for 6 hours.

As the cooking time comes to an end, prepare your hamburger buns. Slice them in half and toast lightly.

After the cooking is complete, spoon generous portions of the meat mixture onto the toasted buns. Add a slice of cheese on top if desired.