1. In a bowl, whisk together the chickpea flour, fennel seeds, salt and water. Add 1/3 cup (75 ml) of the oil and the pastis, if desired. Cover and let rest for 1 hour at room temperature.
2. With the rack in the middle position, preheat the oven’s broiler.
3. Heat a 9-inch (23 cm) cast iron pan over high heat. Add the remaining oil. When the oil is hot, pour in the chickpea flour mixture. Sprinkle with the rosemary leaves and fleur de sel. When bubbles begin to form on the surface, after about 2 minutes, transfer the pan to the oven. Broil for 5 minutes or until the socca is lightly golden.
4.  Slide onto a cutting board. Serve hot or warm, cut into small triangles.

NOTE :
A traditional Niçoise dish, Socca is a large pancake made from chickpea flour. Also known as Farinata in Italy, it is crispy on the outside and soft at the centre. It is often served as an aperitif enjoyed with a glass of rosé.
Chickpea flour can be found in grocery stores among the specialty flours or the gluten-free section.