Slather butter on buns. Heat a large skillet over medium high heat. Add buns and toast for 1 - 2 minutes or until golden brown. Set aside.
Add ground beef to the hot skillet. Break apart into small pieces. Sauté for 5 minutes until beef is no longer pink.
Season with salt and pepper. Add onion and peppers. Cook for another 5 minutes until veggies are tender.
Add the garlic and cook for 1 - 2 minutes. Add the Worcestershire sauce, hot sauce, yellow mustard, brown sugar, and tomato sauce. Stir to combine and bring to a boil. Lower heat to medium low. Add ¼ - ½ cup of water depending on what consistency you like. Simmer uncovered for 10 - 15 minutes. Taste and adjust seasoning if needed.
Scoop mixture onto buns and top with pickles if desired.