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bring a large pot of salted water to a boil over high heat.
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add the olive oil and tomato paste to the skillet and cook over medium-high, stirring frequently, until tomato paste darkens in color and deepens in flavor, about 2 minutes.
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reduce the heat to medium, add the garlic, the anchovy paste and red-pepper flakes, if using, and cook, stirring frequently, until garlic is softened and fragrant, about 2 minutes.
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add the pasta to the boiling water and reduce heat to medium.
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cook according to package instructions until al dente.
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while the pasta cooks, add the cherry tomatoes to the skillet, season with salt and pepper and cook over medium-high, stirring, 5 minutes.
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add 2/3 cup pasta cooking water from the pot and cook, stirring occasionally, until the tomatoes start to fall apart, and the liquid becomes saucy, about 10 minutes.
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drain the pasta and transfer it to the skillet with the sauce to combine.
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stir in half the basil and season to taste with salt and pepper.
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divide among plates or bowls and top with ricotta cheese and whole basil leaves.
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serve immediately.