Bring a large pot of generously salted water to a rolling boil. Add your pasta and cook according to package directions until al dente. Before draining, reserve about 1/2 cup of the starchy pasta water, then drain pasta.

While pasta is cooking, pat chicken cubes completely dry with paper towel and season generously with salt, pepper, and half of the Italian seasoning.

Melt 1 tablespoon butter in a large skillet over medium-high heat. Once butter is shimmering, add chicken in a single layer and sear for 3-4 minutes per side until golden brown and cooked through. Remove chicken from skillet and set aside.

Reduce heat to medium and melt remaining 2 tablespoons butter. Add minced garlic and optional red pepper flakes, and cook for 30-60 seconds, stirring constantly, until garlic is fragrant. Be careful not to burn.

Pour in chicken broth to deglaze the pan, using a wooden spoon to scrape up all the browned bits from the bottom.

Stir in heavy cream and remaining Italian seasoning. Bring sauce to a gentle simmer and let cook for 2-3 minutes to thicken slightly.

Reduce heat to low. Gradually sprinkle in freshly grated Parmesan cheese, stirring gently until completely melted and sauce is velvety smooth.

Add seared chicken and any accumulated juices back into skillet with cream sauce. Add drained pasta as well.

Using tongs, gently toss everything together until pasta and chicken are thoroughly coated in sauce.

If sauce is too thick, stir in small splashes of reserved pasta water until it reaches perfect consistency.

Give it a final taste and adjust with salt and pepper if needed. Serve immediately, garnished with generous sprinkle of fresh parsley.