Cook the rigatoni in salted water according to package directions. Drain, but save about 1/2 cup of the pasta water just in case you need to loosen things up later.
In a large skillet over medium heat, warm the olive oil and butter together until the butter’s melted and foamy.
Toss in the garlic and cook for about 30 seconds until fragrant—don’t walk away here, garlic burns fast!
Add the chopped rotisserie chicken, lemon juice, zest, salt, pepper, and crushed red pepper flakes. Stir to coat the chicken and warm everything through, around 2–3 minutes.
Reduce the heat to low. Pour in the cream and parmesan cheese, stirring until smooth and dreamy. Let it bubble for a minute or two, just until it thickens a bit.
Add the cooked rigatoni into the sauce and toss everything together. If the sauce looks too thick, add a splash of that reserved pasta water.
Top with fresh herbs if you have them. Serve warm and prepare for quiet bites followed by someone asking, 'Wait, you made this?!'