01 - Preheat oven to 400°F.
02 - Place cherry tomatoes, sliced sun-dried tomatoes, and minced garlic in a large ovenproof baking dish. Drizzle with 2 tablespoons olive oil and sprinkle with dried oregano, crushed red pepper flakes, sea salt, and black pepper. Toss to combine evenly.
03 - Position the feta cheese block in the center of the baking dish, nestled among the tomatoes. Drizzle 1 tablespoon olive oil over the feta.
04 - In a large skillet over medium-low heat, add the remaining 1 tablespoon olive oil and sliced onions. Cook, stirring frequently, for 15 to 20 minutes until deeply caramelized and golden brown. Set aside.
05 - Transfer baking dish to the oven and bake for 25 to 30 minutes, or until the tomatoes have burst and the feta is slightly golden on top.
06 - Meanwhile, bring a large pot of salted water to a boil. Cook pasta according to package instructions until al dente. Reserve 1/2 cup pasta cooking water, then drain.
07 - Add caramelized onions to the baked feta and tomato mixture. Gently mash and stir to combine, creating a creamy sauce.
08 - Toss the cooked pasta into the baking dish with the sauce. Add reserved pasta water as needed to achieve desired consistency.
09 - Taste and adjust seasoning with additional salt or pepper if needed. Garnish with torn fresh basil leaves before serving.