How to Make It
In a large, deep skillet, heat the 1/4 cup of olive oil. Add the sliced garlic and crushed red pepper and cook over moderate heat, stirring, until the garlic is golden, about 1 minute. Add the tomato puree, season with salt and simmer the tomato sauce until thickened, 15 minutes.
Meanwhile, bring a large pot of salted water to a boil. Add the spaghetti and cook until pliable but still hard in the center, about 5 minutes. Drain the pasta, reserving 1 1/2 cups of the water.
Add the spaghetti, cooking water and basil sprig to the tomato sauce and cook over moderately low heat, stirring gently, until the pasta is al dente and the sauce is thickened and clings to the strands, 8 minutes longer. Discard the basil sprig. Transfer the spaghetti to bowls. Drizzle with olive oil and garnish with basil leaves. Serve with grated cheese.
The tomato sauce can be covered and refrigerated for up to 5 days.