Season 4 small boneless, skinless chicken breasts on both sides with 1/2 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, 1/2 teaspoon onion powder, and 1/2 teaspoon dried Italian seasoning. (Note: this is not per chicken breast, this is the total amount of seasoning, Feel free to add more to your tastes.)
In a large oven-safe skillet over medium heat, add 1 Tablespoon vegetable oil and 1 Tablespoon butter. Once hot, sear the chicken on both sides until browned, about 5 minutes per side. Place the chicken on a plate.
Wipe out the pan and add 24 ounce jar marinara sauce; bring to a simmer.
Add the chicken back to the pan, cover it, and simmer it until it is cooked through to an internal temperature of 165°F (about 5-10 minutes). Stir occasionally so nothing burns on the bottom. Note: if your chicken breasts are thicker, this may take longer so be sure to go by internal temperature.
Add 4 slices of pepperoni on top of each piece of chicken.
Divide the 1 1/2 cups shredded mozzarella cheese among the four pieces and place on top of the pepperoni.
Top each piece with 4 more slices of pepperoni.
Cover the skillet with a lid and give the cheese a few minutes to melt. Or place under the broiler in the oven until the cheese is browned; keep an eye on it so it doesn't burn (make sure your pan is oven/broiler safe).
Serve immediately with the sauce over cooked pasta of your choice.
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.