Preheat grill to 400° to 450° (high) heat. Cut bread into 40 (1/4-inch-thick) slices, discarding ends. Coat 1 side of each bread slice with cooking spray. Grill bread slices, without grill lid, 1 to 2 minutes on each side.
Cook bacon in a large skillet over medium-high heat 8 to 10 minutes or until crisp; remove bacon, and drain on paper towels, reserving 2 Tbsp. drippings in skillet. Crumble bacon.
Sauté onion in hot drippings 5 minutes or until tender. Stir in beans and next 5 ingredients; cook over medium heat, stirring occasionally, 5 minutes or until thoroughly heated and slightly thickened. Spoon bean mixture onto grilled bread slices. Sprinkle with crumbled bacon. Serve with desired toppings.
Note: We tested with Bush's Best Country Style Baked Beans. Instead of grilling, bread slices may be baked on a baking sheet at 350° for 8 minutes or until lightly toasted.