Pour the 14 ounces of pizza sauce into a small saucepan.

Bring it to a gentle simmer over low heat and cook uncovered for 20 minutes, stirring occasionally.

This is a step I used to skip, but the thicker sauce works much better here. You're trying to cook off some of the extra moisture so it doesn't make the chicken and cheese watery.

After 20 minutes, take the sauce off the heat.

Place each chicken breast on a cutting board and carefully slice it in half horizontally, starting at the thickest side.

You'll end up with 8 thinner chicken pieces.

Place the pieces between two sheets of plastic wrap or parchment paper and gently pound them until they're fairly even in thickness.

You don't need to make them paper-thin. You're just trying to get rid of the really thick middle so everything cooks at roughly the same rate.

And yes, this can get a little noisy. I've definitely regretted doing this when the kitchen is otherwise completely quiet.

Sprinkle the 1 teaspoon salt and 1/2 teaspoon black pepper evenly over both sides of the chicken.

Try to divide the seasoning between all 8 pieces rather than putting most of it on the first few.

Heat 1 tablespoon olive oil in a large oven-safe skillet over medium heat.

Once the oil is hot, add the chicken in a single layer. You may need to work in two batches if your skillet is small.

Sear the chicken for 1 to 2 minutes per side, just until the outside develops a little color.

The chicken does not need to be fully cooked at this point. It will finish cooking in the oven.

If you cooked the chicken in batches, transfer all of the pieces to a lightly greased baking dish in a single layer.

Spoon the thickened pizza sauce evenly over the chicken pieces.

Sprinkle the 1 1/2 cups shredded mozzarella over the top.

Then divide the 1/2 cup sliced pepperoni among the chicken pieces.

I like leaving a few pieces of pepperoni right on top of the cheese because those little edges get nicely browned.

Preheat the oven to 400°F (200°C).

Bake the chicken uncovered for 18 to 22 minutes, or until the thickest piece reaches 165°F (74°C) in the center.

Start checking around 18 minutes because the chicken has already been seared, and thinner pieces can finish fairly quickly.

The cheese should be melted and bubbling around the edges.

If the chicken has reached 165°F but the cheese isn't browned enough for your liking, switch the oven to broil for 1 to 2 minutes, watching it closely. Don't walk away during this part. Cheese can go from nicely browned to burnt pretty quickly.

Let the chicken rest for 3 minutes before serving.