Preheat and Prepare: Preheat the oven to 300°F (150°C) and line a large baking sheet with aluminum foil.
Prep the Ribs: Remove the membrane from the back of the ribs, if present. Place the ribs meat-side up on the foil-lined baking sheet and pat them dry with paper towels.
Mix the Dry Rub: In a small bowl, combine brown sugar, salt, pepper, paprika, garlic powder, onion powder, Italian seasoning, and cayenne pepper.
Coat with mustard: Brush the ribs with mustard, making sure to coat the entire surface (and sides) of the ribs.
Season the Ribs: Sprinkle the dry rub evenly over the entire surface of the ribs. Press gently to help the seasoning adhere.
Wrap and Bake: Wrap the ribs tightly in foil or cover the pan with an additional piece of foil. Bake for 1 1/2 hours, then remove the foil and continue baking for another 1 hour, uncovered.
Make the BBQ Sauce (optional): While the ribs bake, combine all of the BBQ sauce ingredients in a medium saucepan over low heat. Simmer gently, stirring occasionally, until the sauce thickens (about 10–15 minutes).
Brush with Sauce and Bake: Once the ribs are tender, remove them from the oven and generously brush with the BBQ sauce. Return them to the oven and bake uncovered for 20 minutes.
Broil: Switch the oven to broil. Let the ribs broil for 3-5 minutes or until caramelized. Keep a close eye to avoid burning.
Rest and Serve: Let the ribs rest for 5–10 minutes. Slice between the bones and serve with extra BBQ sauce and chopped green onions, if desired.