1) Make the dukkah: Preheat oven to 350 degrees Fahrenheit. Pour the hazelnuts onto a sheet tray, then slip into the oven and toast for about 12 minutes until golden brown and fragrant. Remove from the oven. Pour the nuts onto one half of a clean kitchen towel, and fold over the other half. Rub gently to remove the skins. Chop finely and set aside.
2) Set a cast iron skillet over medium heat. Add the coriander seeds, and toast for a minute or two, then add the cumin and the sesame seeds. Stir often and continue to toast until fragrant, slightly darker in color but not burnt! Stir together the seeds and the hazelnuts, and grind together coarsely in a mortar and pestle. Set aside.
3) Turn oven up to 400 degrees Fahrenheit.
4) Set a large skillet over medium heat. Add the butter and once it has melted and browned
just a little, add the shallots and garlic; cook until softened.
5) Meanwhile, rinse the spinach. Drain, but don’t worry about getting all the water off.
6) Add the spinach to the shallot-garlic mixture, and cook until wilted. Stir in dill, nutmeg, salt
and pepper. Allow to cool slightly, off heat, and then add cheese. Stir well and allow to cool
(you can pop it into the fridge to hurry this along!).
7) Place one puff pastry sheet in the bottom of a pie or square baking dish. Spoon in filling,
using the back of a spatula to level it out. Lay the other sheet of puff pastry on top, and then
crimp the edges, cutting off any excess. Sprinkle with dukkah. Bake on baking sheet for 30
minutes, until golden brown.
8) Sprinkle with sumac. Serve.