To cut the squash into thin, even strips, use a mandoline—a French slicing tool—or one of the inexpensive German or Japanese versions. Plus: More Seafood Recipes and Cooking Tips
Heat 2 tablespoons of the olive oil in a large nonreactive skillet. Add the zucchini and squash, making sure the slices don't stick together, and cook over moderately high heat, stirring often, until barely softened, about 4 minutes. Add the wine and garlic and season with salt and pepper. Add the tomatoes, tomato puree, 1/4 cup of the basil and the heavy cream and boil for 1 minute.
Season the scallops with salt and pepper. In a large heavy skillet, heat the remaining 2 tablespoons of olive oil. Add the scallops in a single layer and cook over high heat until golden on the bottom, about 3 minutes. Turn the scallops and cook just until white throughout, about 1 minute; transfer them to a platter.
Using kitchen tongs, make a nest of the cooked squash in the center of each of 4 heated plates. If the sauce seems to have thinned, simmer until it lightly coats a spoon. Arrange the scallops in the squash nests and spoon the sauce over all. Sprinkle with the remaining basil and serve at once.
Soft and creamy with floral nuances, a northern Italian white wine like Alois Lageder's Pinot Bianco enhances the sweet scallops, zucchini and summer squash.