Remove the baby back ribs from their packaging. Rinse and pat dry with paper towels. Turn the ribs bone side up and trim and remove the silver skin membrane from the ribs. (See post for picture and detailed instructions.)Place ribs on large pieces of heavy duty aluminum foil, large enough to wrap the ribs later.
Sprinkle both sides sparingly with the liquid smoke seasoning.
Combine the brown sugar, chili powder, paprika, salt, pepper, onion powder, mustard, allspice, cumin and cayenne in a bowl. Generously coat both sides of the ribs with the spice rub.
Turn the ribs MEAT side down, then tightly wrap the ribs with the foil. Place the wrapped ribs on a large rimmed baking sheet.
Bake on 275 degrees for about two and a half hours. Remove from the oven and let rest 15 minutes.
Carefully peel back the foil. Brush with sauce as desired and broil for a few minutes until the sauce is sticky and bubbly. Watch carefully and do not burn.