Pour spaghetti sauce into a 10-by-15-inch baking dish, or a rimmed baking sheet. In a large nonstick skillet, heat half of the oil over medium heat. Add half of the chicken, and cook until golden, 1 to 2 minutes per side. Transfer to a paper-towel-lined baking sheet to drain, then place in prepared baking dish. Repeat with remaining oil and chicken.