In a large bowl, whisk together the olive oil, honey, minced garlic, smoked paprika, dried oregano, dried thyme, salt, and pepper. Add the chicken breasts and coat them evenly with the marinade. Cover the bowl and refrigerate for at least 1 hour, or overnight for best results.
When ready to cook the marinated chicken, preheat a grill or grill pan to medium-high heat.
Remove the chicken breasts from the marinade and grill them for 5-6 minutes per side, or until cooked through and charred on the outside. Melt a slice of cheese on the tops of each breast. Set the chicken aside to rest for 5 minutes before preparing the sandwich.
While the chicken is resting, prepare the garlic aioli. In a small bowl, mix together the mayonnaise, minced garlic, lemon juice, salt, and pepper until smooth and creamy.
To assemble the sandwich, spread the garlic aioli on the top and bottom of each hamburger bun followed by a leaf of lettuce, a slice of tomato, chicken, bacon strips (if using), and a slice of red onion (if using). Close the sandwich with the top half of the bun.
Serve the grilled chicken sandwich immediately and enjoy!