Change oven setting to broil and place pan under broiler until the top is brown and blistered, 6-8 minutes. Adjust rack if it browns too quickly or too slowly.
Remove socca to cutting board and cut into wedges.
Sprinkle with olive oil, sea salt and rosemary. Serve warm.
Repeat with remaining batter cooking in batches based on the size of your pan(s).
Makes 1⅔ cups batter. Can easily be halved or doubled.