Bring a large pot of salted water to a boil. Add 8 oz penne pasta and cook according to package instructions until al dente, usually about 10-12 minutes. Drain and set aside, reserving a small cup of pasta water in case you want to loosen the sauce later.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Season 1 lb sliced chicken breast with 1 teaspoon salt and 1 teaspoon black pepper. Add the chicken to the skillet and cook for about 5-7 minutes, flipping halfway, until golden brown and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, reduce heat to medium and add the minced garlic. Sauté for about 30 seconds until fragrant, careful not to burn it. Pour in 1 cup chicken broth, scraping up any browned bits from the pan. Stir in 1 tablespoon lemon juice and 1 tablespoon rinsed capers. Let the sauce simmer gently for 3-4 minutes until slightly reduced.
Return the cooked chicken to the skillet with the sauce. Add the drained penne pasta and gently toss everything together, ensuring the pasta is well coated in the flavorful sauce.
Preheat your oven to 375°F (190°C). Transfer the chicken and pasta mixture into a greased casserole dish. Sprinkle 1/2 cup grated Parmesan cheese evenly over the top. If you like a little heat, sprinkle 1/2 teaspoon red pepper flakes now.
Place the casserole in the oven and bake for 20-25 minutes until the cheese is melted and golden brown on top. Remove from the oven and sprinkle 1/4 cup fresh chopped parsley over the casserole for a burst of color and fresh flavor.