Heat oven to 150C/130C fan/gas 2 and line 2 baking trays with baking parchment. Wash the kale and dry thoroughly. Place in a large bowl, tearing any large leaves into smaller pieces. Drizzle over the oil, then massage into the kale. Sprinkle over the ras el hanout and some sea salt, mix well, then tip onto the trays and spread out in a single layer. Bake for 18-22 mins or until crisp but still green, then leave to cool for a few mins.