Bring a large pot of water to a boil over high heat. When boiling, add the ravioli and cook as per package directions to al dente.
Meanwhile, make the sauce. Heat a small pot over medium heat. Add the butter to melt.
Add the garlic, flour, and sundried tomato paste. Stir and let it cook 2 minutes. It should smell like garlic and/or sundried tomatoes.
Add the heavy cream and milk. Whisk and bring to a simmer. Turn up the heat if needed to medium high.
When simmering, reduce the heat to low and add the Parmesan and mozzarella. Whisk constantly to melt the cheese and let the sauce thicken. Remove from the heat when the cheeses are melted.
Season to taste with salt and black pepper.
Place the ravioli on plates and spoon the sauce over the ravioli. Add additional sundried tomatoes, fresh tomatoes, parsley, or other vegetables if desired.
