Bring a large pot of salted water to a boil. Add the rigatoni and cook until 1 minute less than package instructions; reserve about 1/2 cup of pasta water, then drain the pasta.
Heat a large skillet or saucepan over medium heat and add the olive oil. Add the finely chopped garlic and sauté until fragrant and lightly golden, about 1 minute.
Pour in the diced canned tomatoes, heavy cream, and whole milk. Stir and simmer for 2–3 minutes until combined and slightly reduced.
Add the peeled shrimp and peas to the sauce, season with the salt and pepper, stir, and cook until the shrimp are opaque and cooked through, about 8–10 minutes.
Add the drained rigatoni to the sauce, toss to combine, and cook 1–2 minutes more so the pasta finishes cooking and the sauce thickens; add reserved pasta water a splash at a time if needed to loosen the sauce.
Serve immediately.
