Bring a large pot of water to a rolling boil and add 2 tablespoons kosher salt.
Add 8 ounces cavatappi pasta and cook until 1 minute less than package directions (about 9–11 minutes); reserve 1 cup pasta water, then drain the pasta.
In a large skillet over medium heat, melt 1 tablespoon unsalted butter with 1 tablespoon olive oil.
Add 3 minced garlic cloves and 1 teaspoon Italian seasoning and cook, stirring, until fragrant, about 30 seconds.
Slowly pour in 3/4 cup heavy cream while whisking, bring to a low simmer, then reduce heat to medium-low and cook until slightly thickened, 2–4 minutes.
Stir in 1/2 cup grated Parmesan, 1/2 teaspoon kosher salt, and 1/2 to 1 teaspoon black pepper until the cheese melts into the sauce.
Add the drained pasta and 1/4 cup reserved pasta water to the skillet and toss to coat; cook over medium heat, stirring constantly, until the sauce is creamy and coats the pasta. Add more reserved pasta water 1 tablespoon at a time if the sauce is too thick.
Remove from heat and let rest 1–2 minutes before serving.