Prepare the marinade: In a medium bowl, combine olive oil, chopped chipotle peppers in adobo sauce, minced garlic, honey, cumin, smoked paprika, oregano, salt, pepper, and lime juice. Whisk thoroughly until well combined.

Pound the chicken: Place chicken breasts between two sheets of plastic wrap and pound to an even thickness of about ½ inch. This ensures even cooking and tenderness.

Marinate: Place chicken in a shallow dish or ziplock bag and pour the marinade over it, ensuring all parts are well coated. For best results, refrigerate for at least 30 minutes, or up to 4 hours. If you're short on time, even 15 minutes will impart good flavor.

Prepare the chipotle mayo: While the chicken marinates, mix all chipotle mayo ingredients in a small bowl. Refrigerate until ready to use to allow flavors to meld.

Heat the pan: Heat a large skillet over medium-high heat. Add a tablespoon of oil if needed (the marinade contains oil, so you may not need more).

Cook the chicken: Remove chicken from the marinade and cook for 5-6 minutes on each side, or until the internal temperature reaches 165°F (74°C). The exterior should be nicely caramelized with visible grill marks if using a grill pan.

Rest the chicken: Transfer cooked chicken to a cutting board and let rest for 5 minutes before slicing. This helps retain juices and ensures moist chicken.

Toast the buns: While the chicken rests, lightly butter the cut sides of your brioche buns and toast them in the same pan until golden brown, about 1-2 minutes.

Build your sandwich: Spread a generous amount of chipotle mayo on both sides of the toasted buns. On the bottom bun, layer lettuce, sliced chicken, pepper jack cheese (if using), tomato slices, avocado, and red onion. Top with the upper bun.

Serve immediately: Cut in half if desired and serve while still warm.

For an extra touch, wrap the assembled sandwiches in parchment paper and let them sit for 2-3 minutes. This helps the flavors meld together and makes for a more cohesive sandwich experience.