Bring 4 quarts of heavily salted water to a rolling boil and cook rotini for 8-10 minutes until al dente.
Pat chicken dry and season with kosher salt and black pepper.
Heat olive oil in a large skillet over medium-high heat until shimmering.
Add chicken to skillet and sear for 5-7 minutes, turning occasionally until internal temperature reaches 165 degrees Fahrenheit.
Reduce heat to medium, add minced garlic, and sauté for 60 seconds until aromatic.
Deglaze the skillet with heavy cream, scraping the bottom to incorporate fond, and simmer for 4 minutes until slightly reduced.
Whisk in grated Parmesan cheese until the sauce is emulsified and smooth.
Reserve 0.25 cup of pasta water, then drain the rotini.
Incorporate the pasta into the skillet, tossing with the chicken and sauce until fully coated, adding reserved water if necessary for consistency.
Garnish with chopped parsley and serve immediately.