01 - Set the oven temperature to 400°F.
02 - In a large ovenproof baking dish, combine cherry tomatoes, garlic, and red onion if using. Drizzle with 2 tablespoons of olive oil, season with salt, pepper, and red pepper flakes. Toss to coat evenly.
03 - Place the feta block in the center of the vegetables and drizzle with the remaining 1 tablespoon of olive oil.
04 - Bake in the preheated oven for 30 minutes, until tomatoes blister and feta is golden and soft.
05 - While baking, cook pasta according to package instructions until al dente. Reserve ½ cup pasta cooking water, then drain pasta.
06 - Remove baking dish from oven and mash feta and tomatoes with a fork until creamy.
07 - Add drained pasta and half of the basil to the baking dish. Toss to combine, adding reserved pasta water as needed to achieve a silky sauce.
08 - Plate immediately and garnish with remaining basil and extra black pepper as desired.