Step 1Heat the broiler.
Step 2Sift the chickpea flour with 1/2 teaspoon of salt into a bowl. Slowly add the water, whisking constantly to form a paste. Beat with a wire whisk until smooth. Let the batter stand, covered, at room temperature for 30 minutes.
Step 3In a 10-inch nonstick, ovenproof skillet, heat 1 tablespoon of the olive oil over medium-high heat. Stir the batter and pour 1/2 the batter into the skillet, tipping and swirling it to evenly coat the pan. Cook over medium-high heat until the bottom is golden and crisp and the top is almost set, 2 to 3 minutes. Burst any large air bubbles with the tip of a knife. Sprinkle 1/2 of the tomato and green onions along with pepper to taste on top.
Step 4Place the pan under the broiler and cook until golden and crisp, about 2 to 3 minutes. Slide the pizza onto a work surface. Sprinkle with salt to taste and half the Parmesan cheese. Cut the pizza into wedges and serve hot. Repeat with the remaining batter.