Preheat oven to 400°F. Line a sheet pan with parchment paper.
Place bell peppers and onion onto the pan, season with EVOO, salt, and pepper. Toss to evenly coat. Move peppers and onions to the sides of the pan, leaving the center open.
In a sauce man, bring salsa to a boil. stir to avoid salsa from sticking. Reduce heat to a simmer and continue cooking until the water has evaportated and the salsa resembles a paste.
Season both sides of chicken with salt and pepper. Place chicken into the center of the pan. Spoon salsa paste onto the chicken.
Bake sheet pan for 20 minutes. Turn oven to "broil" and continue cooking for another 3 minutes.
Remove from oven and let rest/cool for 5 minutes. Then, transfer chicken to a cutting board and slice diagionally, perpendicular to the knife [turn chicken breast to the side, horizontially]