Preheat oven to 450 degrees. If desired, pound chicken breasts lightly so they are of even thickness, then dry with paper towels.
Pour oil in a 9x13 baking dish. Roll the chicken breasts through the oil to coat it, then place chicken breasts side by side in the dish.
Combine salt, pepper, onion and garlic powders in a small bowl. Sprinkle mixture over chicken and rub with your hands to coat in the oil and seasonings.
Bake uncovered for 15-20 minutes, or until a meat thermometer reads 160-170 degrees.
While the chicken is baking, make the pesto sauce. Place all the pesto sauce ingredients into a blender or food processor and pulse until smooth. Add more olive oil for a thinner sauce.
Once chicken is out of the oven serve immediately with a dollop of pesto sauce on top. Enjoy!