Note: Chickpea flour is also called besan flour, gram flour and garbanzo bean flour.
Whisk the chickpea flour, water, olive oil, and salt together in a medium bowl. Let rest for 30 minutes to give the flour time to absorb the water.
Set an oven rack 6 inches below your oven's broiler and heat to 450°F. About 5 minutes before your batter's rest is complete, place a 10-inch cast iron skillet under the oven broiler element and turn the oven from 450°F to broil.
Remove the skillet from the oven using oven mitts. Add 1 tablespoon or so of olive oil and swirl to coat the bottom of the pan then scatter the shallots into the pan.
Pour the batter into the pan starting at the edge and working your way to the middle. Tilt the pan so that the batter is against all the edges.
Broil the socca for 5 to 8 minutes or until you see the top of the socca begin to blister and brown, If you find the top browning before the batter is fully set, move the skillet to a lower oven rack until done. The socca should be fairly flexible in the middle but crispy on the edges.
Slice and serve. Use a spatula to work your way under the socca and ease it from the pan onto a cutting board. Slice it into wedges or squares, sprinkle with salt and pepper, and drizzle with a little good olive oil and za'tar.
If your oven does not have a broiler you can set your pan in oven for the 5 min preheat, add batter then place back in oven on top rack and bake 12-15 mins or until the top is nicely browned. To get the bottom of the socca nice and crispy you may have to remove from oven and heat on stovetop for a few more minutes on med/high heat.
Find more of Pamela's gluten free recipes at PamelasGlutenFreeRecipes.com.