bring a large pot of salted water to a boil over high heat.

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.

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.

add the pasta to the boiling water and reduce heat to medium.

cook according to package instructions until al dente.

while the pasta cooks, add the cherry tomatoes to the skillet, season with salt and pepper and cook over medium-high, stirring, 5 minutes.

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.

drain the pasta and transfer it to the skillet with the sauce to combine.

stir in half the basil and season to taste with salt and pepper.

divide among plates or bowls and top with ricotta cheese and whole basil leaves.

serve immediately.