Bring a large pot of salted water to a boil and cook pasta until al dente.
Reserve one cup of pasta water, then drain the pasta.
Season diced chicken with salt and black pepper.
Heat olive oil in a large skillet over medium-high heat and sear the chicken until golden brown and cooked through; remove and set aside.
Melt the butter in the same skillet and sauté the minced garlic for one minute until fragrant.
Whisk in the chicken broth and lemon juice, bringing the mixture to a simmer.
Add the cooked pasta and the seared chicken back into the skillet.
Toss everything together, adding small amounts of the reserved pasta water to emulsify the sauce into a glossy coating.
Stir in the Parmesan cheese and fresh parsley.
Serve immediately while warm.