Preheat an oven to 400 F. Add the cherry tomatoes to a medium-sized casserole dish. Toss them with olive oil, kosher salt, and black pepper.
Step 2
Add the block of feta into the middle of the casserole dish. Top the tomatoes with a few sprigs of fresh rosemary.
Step 3
Bake the dish for 25 minutes or until the cherry tomatoes have split and the cheese is slightly browned on the very edges. Serve hot! Top with fresh red onion.