Set large saucepan over medium heat. Cook bacon 5 to 8 min., until bacon is lightly browned and crisp, but not dry. Transfer bacon to plate and remove all but 2 tbsp (30 mL) bacon fat from saucepan.
Stir bacon, rhubarb, onion, garlic, ginger, allspice and cinnamon into saucepan over medium heat; cook 5 min. or until vegetables are softened. Stir in BBQ sauce and bring to a simmer. Immediately reduce heat to medium-low and continue cooking, stirring occasionally, about 15 min. until thickened. (Cool completely before storing in refrigerator in sealed container for up to 2 weeks.)
Meanwhile, arrange burgers on grill preheated to medium-high heat. Cook 5 to 6 min. per side or until cooked through. Grill buns 1 to 2 min. to lightly toast.
Arrange burger patties on buns and top with 2 tbsp (30 mL) bacon jam. If desired, garnish with arugula, tomato slices and red onion. Serve with baked sweet potato wedges on the side.
Add bacon jam to grilled cheese sandwiches, stir into mac 'n' cheese or serve as a condiment on cheese platters.