Bring a large pot of salted water to a boil. Add the ravioli and the whole Roma tomatoes and cook ravioli according to package directions until al dente and cook tomatoes until their skins start to burst (about the same time as the pasta).
Remove the tomatoes from the pot and let cool until you can handle them. Peel, seed, and dice the tomatoes; set aside. Drain the ravioli in a colander and reserve.
While the pasta cooks, pulse the drained sun-dried tomatoes in a food processor until finely minced; alternatively mince them with a knife.
Heat a large deep skillet over medium heat and melt the butter. Add the minced garlic and sauté about 30 seconds until fragrant.
Sprinkle in the flour and cook, stirring constantly, for 1½ minutes to form a roux.
Slowly whisk in the milk and heavy cream until smooth. Add the minced sun-dried tomatoes and whisk to break up any clumps.
Season the sauce with salt, freshly ground black pepper, and red pepper flakes. Bring to a gentle boil, stirring constantly, until the sauce thickens.
Reduce the heat to low and stir in the Parmesan cheese and the diced Roma tomatoes. Cook, stirring frequently, until the cheese melts and the sauce is smooth. If the sauce is too thick, thin with up to 1/4 cup additional milk.
Add the drained ravioli to the sauce and gently toss to coat. Stir in half of the chopped basil, tossing to distribute evenly.
Serve the ravioli warm, topped with the remaining chopped basil.