Bring a large pot of salted water to a boil and cook the rigatoni until al dente; drain and set aside.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat.
Add the minced garlic, crushed red pepper flakes, and black pepper to the skillet and cook, stirring, for 2–3 minutes until fragrant.
Add the thin chicken strips and the salt, then cook, stirring occasionally, until the chicken is cooked through, about 3–4 minutes.
Pour the marinara sauce over the chicken and stir to combine, then add the heavy cream and mix until smooth.
Let the sauce simmer gently for about 10 minutes, stirring occasionally to thicken and meld flavors.
Stir in the butter and peas until the butter melts and the peas are heated through.
Toss the cooked rigatoni into the sauce until evenly coated.
Serve topped with fresh grated Parmesan and an extra pinch of red pepper flakes if desired.
