Preheat your oven to 375°F and move the rack to the middle position.
Season both sides of each piece of chicken with the garlic powder and salt & pepper.
Add the olive oil to a large skillet over medium-high heat. Once the pan is hot, sear the chicken for about 5 minutes on each side until golden brown.
Transfer the seared chicken to a 9×13 casserole dish.
Pour in the pizza sauce and spoon it evenly over and around the chicken.
Sprinkle the mozzarella generously over each piece of chicken.
Top the chicken breasts with the tomato slices and pepperoni.
Bake uncovered for about 20 minutes. If your chicken breasts are smaller, check for doneness around 15 minutes.
After baking, let the chicken rest for 5 minutes.
Finally, sprinkle with freshly torn basil before serving.