In a bowl, combine all the ingredients well.
Season the ribs with 1/3 cup (80 ml) of the rub and place them on the grill.
Fill the spray bottle with apple juice, reserving 2 tablespoons (30 ml).
Smoke the ribs over indirect heat for about 2 hours or until nicely browned and smoked. Spray with apple juice as needed so the ribs don’t dry out.
On a large sheet of foil, arrange the slices of butter in a line. Add 1 tablespoon (15 ml) of the rub and the 2 tablespoons (30 ml) reserved apple juice. Place the ribs meat side down on the butter (bone side up) and close up the foil to make a pouch. Cover with another layer of foil to seal as tightly as possible.
Return the meat to the smoker and continue cooking over indirect heat for about 2 hours or until you can see the meat pulling away from the ends of the bones (check by carefully opening the pouch) and the internal temperature of meat reaches 205°F (96°C).
Unwrap the ribs, put them back on the grill, then increase the temperature of the smoker to 300°F (150°C). With a brush, baste with baby-cue sauce to taste and smoke for about 1 hour.