Heat the olive oil in a large pot or deep skillet over medium-high heat.
Add the chicken pieces and cook for 5-6 minutes until browned on all sides and cooked through. Remove the chicken from the pot and set aside.
In the same pot, add the chopped onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Pour in the diced tomatoes with their juice, chicken broth, and add the uncooked penne pasta.
Stir in the dried Italian seasoning, salt, black pepper, and crushed red pepper flakes.
Bring the mixture to a boil, then reduce the heat to medium-low and simmer uncovered for 12-15 minutes, stirring occasionally, until the pasta is cooked and most of the liquid is absorbed.
Return the cooked chicken to the pot and stir to combine. Cook for an additional 2 minutes to heat through.
Remove the pot from heat and stir in the grated Parmesan cheese and chopped fresh basil.
Serve immediately, garnished with extra Parmesan and basil if desired.