Bring a large pot of salted water to a boil and cook the penne according to the package directions.
Before draining, reserve ½ cup of the pasta cooking water. Drain the pasta and set aside.
Heat 2 tablespoons olive oil in a large skillet over medium heat.
Add the chicken strips and cook for 5–8 minutes, stirring occasionally, until fully cooked and no longer pink. Season with the salt and black pepper.
Stir in the chopped red, yellow, and orange bell peppers along with the diced shallots. Cook for 4–7 minutes until the vegetables begin to soften and lightly caramelize.
Add the minced garlic and cook for another minute until fragrant.
Stir in the balsamic vinegar, lemon juice, remaining tablespoon of olive oil, reserved pasta water, and cooked penne. Toss everything together and cook for 3–4 minutes until the sauce lightly coats the pasta. This Chicken Vegetable Skillet Pasta comes together beautifully as the flavors blend.
Transfer to a serving platter and sprinkle with parsley before serving.