Heat the vodka sauce, water, and eggplant mixture in a large pot over medium-high heat. Bring to a gentle boil.
Add the rigatoni pasta to the pot and stir to combine. Turn the heat down to medium-low and let the sauce simmer for 5 minutes, stirring periodically to prevent sticking.
Add the frozen spinach to the pot and stir until it thaws and warms. Continue to simmer until the pasta is cooked to al dente.
Remove from heat, top with parmesan cheese, and serve immediately.
Notes
This recipe is quick, creamy, and perfect for a satisfying dinner.