Bring a large pot of salted water to a boil and cook the penne pasta until al dente according to package instructions, reserving 0.5 cup of pasta water before draining.
While the pasta cooks, melt the butter in a large skillet over medium heat.
Add the minced garlic to the skillet and sauté for 60 seconds until fragrant but not browned.
Whisk in the flour and cook for 1 minute to create a roux, stirring constantly to prevent clumping.
Slowly pour in the chicken broth and heavy cream, whisking continuously to ensure a smooth texture.
Bring the mixture to a gentle simmer and cook for 3-5 minutes until the sauce thickens enough to coat the back of a spoon.
Stir in the Italian seasoning, salt, black pepper, and red pepper flakes.
Reduce the heat to low and whisk in the Parmesan cheese until completely melted and the sauce is glossy.
Add the drained penne to the skillet and toss vigorously to coat, adding reserved pasta water 1 tablespoon at a time if the sauce is too thick.
Garnish with fresh chopped parsley and serve immediately.