In a small mixing bowl, combine minced garlic and jalapeño. With a sharp knife, pierce 6–8 (1-inch) holes in roast and stuff each cavity with mixture. In a separate mixing bowl, combine salt, black pepper, granulated garlic, cumin, onion powder, chilli powder, cayenne pepper, paprika and brown sugar. Place roast in an aluminum pan and season well with seasoning mixture. Using an injector, inject roast with Creole Butter marinade. Cover tightly with clear wrap and place in refrigerator overnight. Place roast in a 12-quart, cast iron Dutch oven and set aside at room temperature for at least 1 hour prior to baking. When ready to cook, preheat oven to 500°F. NOTE: It is important to preheat oven for 30 minutes before placing roast in the oven. It will ensure the heat reaches 500°F. Cover Dutch oven with lid and bake in oven for 1 hour. Turn oven heat off and leave roast in oven for 11 hours or overnight. Do not open the oven during the entire cooking process. When ready to serve, remove roast from oven and allow to cool slightly then thinly slice. Serve with your favorite barbecue sauce and toasted po'boy buns. NOTE: It is recommended to begin the baking process 12 hours prior to serving so the roast can be served warm immediately out of the oven. For example, if you wish to serve the roast at noon, the pot with roast should go into the oven at midnight. However, it can be reheated in oven right before serving. NOTE: If you wish to cook roast in a conventional manner, preheat oven to 350°F. Insert digital thermometer into roast then cover tightly with lid. Cook until internal temperature reaches 195°F–200°F, 3 to 4 hours.