01 - Set oven to 400°F.
02 - Add cherry tomatoes, minced garlic, and sliced red onion (if using) to a large ovenproof baking dish. Drizzle with half the olive oil. Sprinkle with salt, black pepper, dried oregano, and red pepper flakes. Toss to evenly coat.
03 - Clear a space at the center of the dish and place the feta cheese block in the middle. Pour the remaining olive oil over the cheese.
04 - Bake for 30 to 35 minutes, until tomatoes are blistered and feta is golden and softened.
05 - In a large pot, boil salted water and cook pasta until al dente according to package directions. Reserve 1/2 cup of pasta water, then drain.
06 - Remove baking dish from oven. Use a fork to mash feta and roasted tomatoes together, forming a creamy sauce.
07 - Add cooked pasta to the baking dish. Toss thoroughly to coat the pasta, adding reserved cooking water as needed for desired consistency.
08 - Stir in torn fresh basil. Adjust seasoning with additional salt and black pepper to taste.
09 - Plate immediately and garnish with more fresh basil if desired.