Heat the first 2 1/4 cups (500 ml) water with the butter and a splash of olive oil.
Place the chickpea flour into a large mixing bowl, and gradually pour in the cold water, beating until the mixture is uniform.
Strain through a fine conical strainer, and pour into the boiling water. Simmer over a low heat for 20 minutes, stirring often.
In the meantime, make the Aglio Olio:
Add olive oil to a small pan over med-low heat.
Add smashed garlic, rosemary sprigs and salt.
Cook on low until batter is ready, careful not to burn garlic. Strain and add oil to batter.
Grease a square cake and pour in the batter. Tap against the counter to remove any air bubbles.
Cover with cling film and allow to cool, then refrigerate for 30 minutes.
Once cooled and formed, empty onto a plate. Cut horizontally once, then cut into 2 inch squares.