Sift the chickpea flour with the salt into a medium bowl. Slowly add 1/2 cup of the water, whisking constantly to form a paste. Whisk until smooth. Whisk in the remaining 1/2 cup of water and let the batter stand at room temperature for 30 minutes, then stir in the rosemary.
Heat 1 tablespoon of the olive oil in a 12-inch nonstick ovenproof skillet or pan. Stir the batter once, pour it into a hot skillet and drizzle the remaining 2 tablespoons of olive oil on top. Cook the pizza over moderately high heat until the bottom is golden and crisp and the top is almost set, 2 -3 minutes. Burst any large air bubbles with the tip of a knife.
Top with your favourite pizza toppings and then place the skillet under the grill and cook until the pizza is golden and crisp, approximately 4 to 5 minutes.
Slide the pizza onto a work surface, cut into wedges and serve hot.
Try any flavor combination including: prosciutto, goats cheese and basil or grilled vegetables and parmesan or tomato, shaved ham and mozzarella.