Bring a large pot of salted water to a boil. Add the ravioli and the two whole Roma tomatoes and cook ravioli according to package directions until tender and cook tomatoes until their skins burst, about 6 minutes; if tomatoes do not burst, cut an X in the bottom and boil 2 minutes longer.
Remove tomatoes with a slotted spoon and set aside to cool until manageable. Drain the ravioli and keep warm.
When cool, peel the tomatoes, remove seeds, and dice the flesh; set aside.
While the pasta cooks, place the drained sun-dried tomato halves in a food processor and pulse until finely minced, or mince finely with a knife.
In a large, deep skillet over medium heat, melt the butter. Add the minced garlic and sauté about 30 seconds until fragrant.
Stir in the flour and cook, stirring constantly, for 1½ minutes to form a roux.
Whisk in the milk and heavy cream gradually 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 to taste. Bring to a light boil, stirring constantly, until the sauce thickens.
Reduce heat and stir in the Parmesan and the diced Roma tomatoes; cook, stirring frequently, until the cheese has melted and the sauce is smooth. Thin with an additional 1/4 cup milk if desired.
Add the cooked ravioli to the sauce and gently toss to coat. Stir in half of the chopped basil.
Serve warm, topped with the remaining chopped basil.