Prepare batter by whisking 1 cup of chickpea flour with 1 tsp salt and 1 tsp black pepper.
Slowly whisk in one cup of warm water.
Add 2 TBSP extra virgin olive oil to the batter.
Cover and put in fridge, ideally 8-12 hours. It is also fine to just prepare batter and cover while oven is pre-heating, but best batter consistency is rested for 8-12 hours.
Preheat oven to 425°F
Use 1 TBSP olive oil to generously grease 9-inch round baking dish.
Sautee onion in 1/2 tsp olive oil for 3 minutes on medium-high heat.
Immediately pour sautéed onions into the prepared baking dish. Add finely chopped rosemary to onions.
Pour batter over the onions and rosemary and mix well so the batter, onions, and rosemary are evenly distributed to fill the dish.
Bake in oven 10-15 minutes, until batter is firm and edges are set. I prefer 10 minutes.
Brush top with 1-2 tbsp extra virgin olive oil.
Set broiler on high and broil for 2 minutes to get nice brown spots on top.
Drizzle 1-2 tbsp olive oil (optional) and serve immediately.
If any manage to make it as leftovers, store in fridge 3-5 days in air tight container.