Step 1: Preheat your oven to 400°F (200°C). On a large baking sheet, toss the cherry tomatoes with olive oil, salt, and pepper.
Step 2: Roast the tomatoes for 15-20 minutes, or until they are soft and have started to burst. Remove from the oven and set aside.
Step 3: While the tomatoes are roasting, cook the pasta in a large pot of boiling salted water according to the package directions until al dente.
Step 4: Before draining the pasta, reserve about 1/2 cup of the starchy pasta cooking water.
Step 5: In a large mixing bowl or back in the pot, combine the drained pasta with the basil pesto and the roasted tomatoes (including the juices).
Step 6: Gradually add the reserved pasta water, a little at a time, tossing the mixture until the pesto coats the pasta smoothly.
Step 7: Serve immediately, garnished with Parmesan cheese, fresh basil, and a pinch of red pepper flakes if desired.