Bring a large pot of salted water to a rolling boil. Add the spaghetti and cook until al dente, about 8 to 10 minutes. Reserve ½ cup pasta water, then drain and toss with olive oil.

In a large skillet, melt 2 tablespoons unsalted butter and 2 tablespoons olive oil over medium-low heat. Add minced garlic and sauté for 1 to 2 minutes until fragrant and lightly golden.

Sprinkle in Italian seasoning and lemon zest, stirring to combine. Allow to toast for about 30 seconds.

Add lemon juice and increase heat to bring mixture to a gentle simmer. Cook for 1 to 2 minutes, stirring occasionally.

Add drained spaghetti to the skillet, tossing to coat. Gradually add reserved pasta water, stirring until the sauce emulsifies and coats the pasta.

Remove skillet from heat and fold in fresh parsley. Season with kosher salt and freshly cracked black pepper to taste. Adjust lemon juice or zest if needed.

Plate the pasta and finish with grated Parmesan cheese and crushed red pepper flakes if desired. Serve immediately.