JALEPENO Ketchup: Combine all ingredients in small saucepan. Bring to boil on medium-high heat, stirring frequently. Reduce heat to medium-low; simmer 20 min. or until thickened, stirring occasionally.
BURGERS: GRILL patties on medium-high heat 2 min. on each side or until medium doneness (160ºF), brushing half of the burgers with half of the Jalapeno Ketchup and remaining burgers with half of the barbecue sauce immediately after turning. Turn burgers over again; brush with remaining Jalapeno Ketchup and remaining barbecue sauce. Top each ketchup-topped burger with 2 VELVEETA Slices and each barbecue sauce-topped burger with 2 American cheese slices. Continue grilling 1 min. or until cheese is melted.
MEANWHILE, mix buttermilk and 3 Tbsp. of the dressing mix (or 1 Tbsp. of the dressing mix for trial recipe); set aside. Mix flour and remaining 3 Tbsp. dressing mix (or remaining 1 Tbsp. dressing mix for trial recipe).
SEPARATE yellow onions into rings. Add to buttermilk mixture; let stand 10 min. Drain onions. Add, in batches, to flour mixture; toss to coat. Add, in batches, to deep-fat fryer heated to 350ºF. Cook 2 to 3 min. or until golden brown; drain.
FOR each serving: Place 1 American cheese-topped burger on bottom half of roll. Top with 1-1/2 oz. of the fried onion rings, 1 tsp. of the bacon pieces and 1 VELVEETA-topped burger. Cover with 1 slice each grilled tomatoes and grilled red onions, 1 oz. shredded lettuce and top of roll.