In a medium bowl whisk together chickpea flour, parsley, garlic, kosher salt, and chili powder. Add water and 2 Tbsp. of the olive oil. Whisk until smooth. Let batter stand 15 minutes.
Meanwhile, preheat broiler. Add 1 tsp. of the oil to 10-inch cast-iron or heavy oven-going skillet. Place the skillet in upper one-third of oven to preheat 5 minutes (bottom of pan should be 5 inches from heat). Holding handle of skillet with hot pads, pour half the batter (about 3/4 cup) into skillet; carefully spread the batter evenly using an offset spatula.
Return skillet to oven and broil about 4 minutes or until golden brown and slightly dark brown in some areas. Loosen from skillet with wide spatula and transfer to paper towels. Repeat with remaining batter, preheating skillet with the remaining 1 tsp. oil 1 minute before adding the remaining batter. Serve at room temperature or reheat socca in 350 degrees F oven on baking sheet 5 minutes. Cut rounds in half.