01 - Bring a large pot of salted water to a boil. Cook rigatoni until al dente following the package directions. Reserve 1/2 cup pasta water, drain, and set aside.
02 - Season chicken pieces evenly with salt, black pepper, and dried Italian herbs.
03 - Heat olive oil in a large skillet over medium-high heat. Add chicken and cook, stirring occasionally, until golden brown and cooked through, about 5 to 7 minutes. Transfer chicken to a plate and set aside.
04 - Reduce skillet heat to medium. Add butter and minced garlic; sauté until fragrant, approximately 1 minute.
05 - Sprinkle in all-purpose flour, whisking constantly for 1 minute to develop a roux.
06 - Gradually pour in whole milk and heavy cream while whisking to avoid lumps. Bring to a gentle simmer.
07 - Stir in grated Parmesan cheese and ground nutmeg. Season the sauce with additional salt and pepper to taste. Simmer until sauce thickens, about 2 to 3 minutes.
08 - Return cooked chicken to the skillet. Add drained rigatoni and gently toss to coat in sauce, incorporating reserved pasta water as needed for desired consistency.
09 - Plate immediately and garnish with fresh parsley and extra Parmesan.