01 - Bring a large pot of salted water to a boil. Cook penne according to package directions until al dente. Drain and set aside, reserving 1/2 cup pasta water for adjusting sauce consistency later.
02 - Heat olive oil and 1 tbsp butter in a large skillet over medium-high heat. Add seasoned chicken pieces and cook until golden brown and cooked through, approximately 6–8 minutes. Transfer to a plate and cover to keep warm.
03 - Reduce heat to medium in the same skillet. Add remaining 1 tbsp butter and minced garlic. Sauté until fragrant, about 1 minute, being careful not to burn the garlic.
04 - Pour in heavy cream and whole milk, stirring continuously to combine. Simmer gently for 3–4 minutes until the mixture begins to thicken slightly.
05 - Reduce heat to low. Gradually whisk in Parmesan cheese until completely melted and the sauce is smooth. Season with a pinch of nutmeg and adjust salt and pepper to taste.
06 - Return cooked chicken to the skillet, add drained penne, and toss thoroughly to coat. If sauce consistency is too thick, add a splash of reserved pasta water until desired coating is achieved. Remove from heat, garnish with chopped parsley, and serve immediately.