Prepare the tomato mixture. In a medium bowl, add the olive oil, lemon juice, tomatoes, olives, onion, garlic, oregano, black pepper, and red chili flakes (if using), and toss until combined.
Assemble. Place the feta cheese into a small, rimmed casserole dish. Add the tomato mixture making sure the feta is sitting in the center of the dish and isn't covered by the tomatoes. Top with fresh rosemary and extra black pepper and red pepper flakes, if desired.
Bake for15-20 minutes or until the feta has softened. Serve immediately with Pita bread, bread of choice or crackers.
Notes
Make-Ahead Instructions: this feta dip can't be made ahead of time as feta hardens up as it cools down.Storing Instructions: store leftovers covered in the refrigerator for up to 2-3 days. Keep in mind that the feta will go back to its original firm texture once cooled down and stored.