1. Fill a pot for the pasta with about 6 quarts of water, place over high heat, and bring to a boil.
2. Peel the tomatoes and coarsely chop them. Peel the garlic clove and finely chop it.
3. Put the garlic, hot red pepper flakes, and the olive oil in a 12-inch skillet and place over medium-high heat. As soon as the garlic begins to sizzle, add the tomatoes. Season with salt and cook until the liquid the tomatoes release has evaporated, 10 to 12 minutes.
4. While the tomatoes are cooking, cut the scallops into ¼-inch dice.
5. When the tomatoes are ready, add about 2 tablespoons salt to the boiling pasta water, add the spaghetti, and stir until all the strands are submerged. Cook until al dente.
6. Shred the basil leaves and add them to the pan with the tomatoes. Raise the heat to high and add the scallops. Cook until the scallops are done, 1 to 2 minutes, then remove from the heat.
7. When the pasta is done, drain well, toss with the sauce, and serve at once.