Rinse and halve tomatoes. Rinse scallions and cut into rings. Heat olive oil in a pan and saute tomatoes for 1-2 minutes on high heat. Peel garlic and squeeze through a press, add to the pan together with scallions. Season with salt and pepper and keep warm.
Cook tagliatelle according to package instructions in boiling salted water until al dente. Rinse basil, shake dry and pluck off leaves. Drain tagliatelle well. Add pasta and basil to tomatoes and mix well. Arrange on plates, sprinkle with Parmesan and serve.