Heat olive oil in a large skillet over medium heat.
Add the crumbled turkey sausage to the skillet and cook, stirring occasionally, until browned and cooked through, about 6-8 minutes.
Add the diced onion to the skillet and cook until softened, about 3-4 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Pour in the diced tomatoes with their juice and tomato sauce, stirring to combine.
Add the dried Italian seasoning, crushed red pepper flakes, salt, and black pepper. Stir well.
Pour in the chicken broth and bring the mixture to a simmer.
Add the penne pasta to the skillet, stirring to submerge the pasta in the sauce.
Cover the skillet and cook over medium-low heat until the pasta is tender and most of the liquid is absorbed, about 12-15 minutes. Stir occasionally to prevent sticking.
Remove the skillet from heat and stir in the grated Parmesan cheese until melted and combined.
Sprinkle the chopped fresh parsley over the top before serving.