Pour chickpea flour into a bowl and gradually add water. Whisk gently until the batter is smooth.
Add salt, pepper, 3 tablespoons of olive oil into the batter.
Cover the bowl with plastic wrap and set aside for 1 hour. Optional: You can leave the batter overnight in the fridge for extra flavor.
After 1 hour uncover the batter. Use a small spoon to skim the foam from the top of the batter.
Finely chop the onion. Add the onions to a pan and brown for 5 mins. Cut the black olives in half and set aside.
Preheat the oven to 450℉.
Add olive oil (about 2 tablespoons) to a non-stick pan or skillet. Pour the chickpea batter and add the browned onions and olives. Add in 2 teaspoons of rosemary.
Bake for 20-25 mins. Cook just long enough until the top looks is brown.
Brush with extra olive oil if top looks dry. Cut the farinata into wedges and serve warm.
