Prepare the chicken. Place one chicken breast onto a sheet of parchment paper, then fold the paper over the chicken. Use a rolling pin to pound the chicken breast to an even thickness of just under 1”. Set aside and repeat with the remaining chicken breasts. Arrange the chicken breasts in a single layer in a casserole dish.
Combine the lime juice, olive oil, and honey in a mixing cup or bowl; whisk until the honey is dissolved. Add the jalapeños, lime zest, garlic, chili powder, and salt and whisk once more. Pour the marinade over the chicken breasts; use your (clean) hands to massage the marinade into the chicken, then cover with plastic wrap or a kitchen towel. Transfer the chicken to the fridge; marinate at least 30 minutes, ideally for 2 hours, and up to 8 hours.
Heat a grill or grill pan over high heat. Place the chicken on the grill; cook 5-6 minutes and baste with several times with the remaining marinade. Flip the chicken, cease basting, and grill 5-6 minutes more, or until an instant read thermometer registers 165°F.
Remove the chicken from the grill to a cutting board and rest for 5 minutes. Slice against the grain and garnish with chopped cilantro and thinly sliced jalapeno.
