Brick, or warka, pastry is a very fine, crispy pastry, not too dissimilar to filo and used extensively in North African cooking.
Start the filling. Heat 1 tablespoon of the olive oil in a large pan over a medium heat. When hot, add the diced chicken and cook for 15 minutes, until cooked through. Remove from the pan and set aside to cool.
While the chicken is cooling, start the pastry. Sift the flour, semolina, salt, lemon juice and olive oil in a bowl and mix well. Make a well in the centre and add 250ml of water. Beat until smooth with a wooden spoon, or blitz with a hand-held blender, to a smooth, flowing batter.
Bring a large pan of water to the boil, then reduce to a simmer. Place the large, non-stick flatbread pan on top of the pan of water. Pour a little vegetable oil onto the surface and spread with kitchen paper. (Note you do this only once at the start of the process.)
Using a 5cm pastry brush and working from the outside edge of the pan, paint the batter thinly in circles, until the whole pan is covered in a thin layer of batter. Cook for 2–4 minutes, until the brick pastry begins to peel away from the edges.
Lift the brick off the pan (it should be as thin as filo pastry and have no holes) and lay it on a sheet of kitchen paper. Lightly brush the surface with vegetable oil and place another sheet of kitchen paper over the top to prevent it drying out. Repeat steps 3–5, until you have 12 sheets of brick interleaved with kitchen paper. Set aside while you finish the filling.
Heat the oven to 220°C/200°C fan/Gas 7. Tip the butternut and sweet potato onto a roasting tray. Drizzle with 2 tablespoons of the olive oil and sprinkle over the ras el hanout and salt. Using your hands, mix to coat the vegetables in the oil and seasoning. Roast for 20 minutes, then remove from the oven and set aside to cool. Reduce the oven temperature to 200°C/180°C fan/Gas 6.
Heat the remaining 2 tablespoons of olive oil in a deep-sided frying pan or large saucepan and add the onions and garlic. Cook on a low heat for 5 minutes, until starting to soften, then add the harissa paste, fennel seeds, cumin seeds, ginger and cinnamon. Cook for 2 minutes, then stir in the pomegranate molasses, dates, apricots and chickpeas.
Crumble in the stock cube, then pour in 250ml of water and cook, stirring for 4–5 minutes, until the sauce has reduced to almost nothing and the mixture is sticky. Remove from the heat and stir in the coriander, parsley and lemon juice. Tip into a shallow tray and set aside to cool, then carefully fold in the roasted squash and sweet potato and stir in the chicken.
Lay one sheet of brick in the prepared tin, so that one edge sits in the middle of the tin and the opposite edge is overhanging the tin. Continue lining the tin with another 7 sheets of brick, overlapping each other around the inside of the tin and overhanging the edge. Place a 9th sheet on the base of the tin and brush with butter.
Spoon the filling into the tin, then fold over the overhanging brick, scrunching up over the filling and giving the brick some texture. Don’t worry if the brick doesn’t cover the filling. Brush the 3 remaining sheets of brick with butter, then scrunch them up and press them over the top of the pie, to cover any gaps and hide the filling.
Place on a baking sheet and bake for 30–35 minutes, until the brick is crisp and golden brown and the pie is cooked through. (Cover with foil after 20 minutes if the top is beginning to brown too much.) Leave to cool in the tin for 5 minutes, then remove from the tin and serve.