Place all ingredients in the blender. Puree until frothy. Then allow the batter to rest for at least 2 hours, but up to 6 hours.
Preheat the broiler to 500 degrees F. Adjust the highest oven rack to 6-7 inches below the broiler and place a large round pizza pan on the rack to heat.
When the pan is scalding hot, carefully pull out the oven rack and spray the pan thoroughly with nonstick cooking spray. (It will sizzle and cloud a little, but it's important to do this immediately before adding the batter.)
Pour half the batter on the pizza pan in a circular motion. Using an oven mitt, quickly jiggle the pan a little to help it spread. Then close the oven door and set the timer for 3 minutes. Check after 3 minutes, and allow the socca to broil another 2-3 minutes if need. Remove when the edges are firm and black char marks form on the surface.
Run a large flat metal spatula under the socca and move it to a cutting board. Cut into 2-inch squares and sprinkle with salt and pepper. Repeat with the remaining batter.