1. Heat the olive oil in a medium skillet over medium-high. Add the onion and garlic, and cook, stirring often, until the onion is softened and very lightly browned, about 6 minutes. Remove from the heat, and cool slightly.

2. Stir together the breadcrumbs, milk, parsley, Worcestershire, salt, pepper, egg, and 1/4 cup of the ketchup in a large bowl. Add the ground meat, and gently combine using your hands. Let the mixture stand for 5 minutes.

3. Preheat the grill to medium (350°F to 450°F). Shape the meat mixture into 10 (about 1/4-pound) patties. Using your finger, make a slight indentation into the middle of each patty. (This helps to allow for plumping while the patty cooks on the grill.)

4. Stir together the mayonnaise, brown sugar, Sriracha, and remaining 1/4 cup ketchup in a small bowl.

5. Place the patties on oiled grates; grill, covered, until they are no longer pink in the center, 4 to 5 minutes per side, arranging 1 slice of cheese on top of each patty during the last few minutes of grilling. Serve the patties in the ciabatta rolls each topped with 2 bacon halves, pickles, and dollops of the Sriracha mixture. Serve immediately.