Preheat the oven to 425 degrees F.
In a bowl, stir together the brown sugar, cumin, chili powder, smoked paprika, garlic powder, chipotle chili powder, salt and pepper.
Rub the spice mixture all over the chicken breasts, reserving a bit for the peppers and onions. Place the chicken on the sheet pan and surround it with the sliced peppers and onions. Sprinkle the remaining spices over top. Sprinkle the corn all over the sheet pan.(As a note, you can also use frozen corn, it may release a bit more liquid.)
Roasted for 20 to 25 minutes, or until the chicken is cooked through. Use a cooking thermometer to test the internal temperature, which should be 165 degrees If at any time the peppers and onions look like they may burn, you can pull out the sheet pan and toss the veggies with a fork.
Let the chicken cook for 5 to 10 minutes before slicing or shredding. Sprinkle the pico de gallo on top along with the cotija cheese. Serve with extra lime wedges, guacamole, jalapenos and cilantro.