Preheat the oven to 425°F (220°C) and line a rimmed baking sheet or lightly oil it.
In a mixing bowl, combine the brown sugar, cumin, chili powder, smoked paprika, garlic powder, chipotle chili powder, 1/2 teaspoon salt, and 1/2 teaspoon black pepper.
Rub most of the spice mixture evenly over the chicken breasts, reserving a small amount to season the peppers and onions.
Place the seasoned chicken on the prepared sheet pan and arrange the thinly sliced bell peppers and thinly sliced red onion around the chicken. Sprinkle the reserved spice mix over the vegetables.
Scatter the corn over the sheet pan, then add the quartered cherry tomatoes and the diced half sweet onion around the chicken.
Roast in the preheated oven for 20 to 25 minutes, until the chicken reaches 165°F (74°C) internal temperature and the vegetables are tender; if vegetables look like they are burning, remove the pan briefly and toss them with a fork.
Remove the sheet pan and let the chicken rest for 5 to 10 minutes, then slice or shred the chicken.
While the chicken rests, toss the quartered cherry tomatoes, diced sweet onion, chopped cilantro (1/4 cup), and lime juice together in a bowl; season with a pinch of salt and pepper to make a quick pico.
Top the sliced or shredded chicken and roasted vegetables with the pico de gallo and sprinkle with cotija cheese. Serve with extra lime wedges, guacamole, sliced jalapeños and additional cilantro as desired.