Heat olive oil in a large deep skillet or pot over medium heat.
Add the chopped onion and sauté for 3-4 minutes until softened and translucent.
Add the minced garlic and cook for 1 minute until fragrant, stirring frequently to avoid burning.
Add the dried penne pasta to the pot, then pour in the chicken broth, whole milk, and heavy cream.
Stir in the salt, black pepper, and dried Italian seasoning.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered, stirring occasionally, for 15-18 minutes or until the pasta is tender and the liquid has mostly absorbed.
Remove the pot from heat and stir in the grated Parmesan cheese until melted and the sauce is creamy.
Adjust seasoning with additional salt and pepper if needed.
Serve immediately, garnished with extra Parmesan if desired.