Heat a large skillet over medium high heat and coat with oil. Season the chicken with the salt, pepper, oregano, and garlic on both sides. Place the chicken in the skillet, and let it cook, undisturbed, for about 4 minutes, or until browned on the bottom. Flip and cook another 4-5 minutes or until the internal temperature registers 160 degrees. Remove the chicken to a plate and cover to keep warm.
With the heat still on medium high, add a splash of water to the pan and scrape up any browned bits. Add the jarred sauce to the pan and let it simmer for 2-3 minutes. Return the chicken to the pan and flip to cover with sauce.
Top each chicken breast with a few slices of mozzarella and pepperoni and a little shredded Mexican cheese blend, if desired. Cover the pan with a lid or baking sheet, and allow cheese to melt for 1-2 minutes.
As soon as the cheese is starting to melt, remove the pan from heat and place it under the broiler. Broil for 2-3 minutes or until browned and bubbly. Remove and garnish with fresh basil, if desired. Pizza chicken can be served on its own or over pasta.