Preheat oven to 400°F (200°C). Cook pasta in salted water according to package directions until al dente; drain, reserving 1 cup of the starchy pasta water.
Place the block of feta in the center of a 9x13-inch baking dish. Arrange roasted red peppers and olives around it. Sprinkle minced garlic, red pepper flakes (if using), and a good pinch of salt and pepper over everything. Drizzle evenly with olive oil.
Bake for 25-30 minutes, until the feta is soft and slightly golden, and the peppers are caramelized at the edges.
Remove the dish from the oven. Immediately add the hot cooked pasta and a splash of reserved pasta water. Use tongs or a spoon to break the feta apart and toss vigorously until a creamy sauce forms and coats all the pasta. Add more pasta water, a little at a time, until you reach a silky consistency.
Stir in lemon zest and juice, if using. Taste and adjust seasoning with salt and pepper. Scatter fresh basil over the top and serve immediately, either straight from the baking dish or transferred to a warm serving bowl.