Bring a large pot of lightly salted water to a boil. Cook rigatoni in the boiling water, stirring occasionally until cooked through but firm to the bite, about 13 minutes. Drain.

Meanwhile, place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Remove bacon with a slotted spoon, leaving drippings in pan; set bacon aside.

Cook and stir garlic in the remaining bacon grease over medium heat. Add milk, cream cheese, and butter to skillet; stir until smooth.

Stir Parmesan cheese, peas, ham, and cooked bacon into the cream cheese mixture; cook until peas are heated through, about 5 minutes more.