Preheat oven to 100C (200F) for overnight cooking or 150C (300F) for 4 hours cooking.
Heat the olive oil in a large pan that has a lid over medium high heat. Add the onions and saute until lightly brown. Add the whole garlic, paprika, ras el hanut, salt and pepper; stir for a couple of minutes. Add the Israeli couscous and lightly toast it, stirring constantly. Add the water, cover, and cook the couscous for 8 minutes or until the liquid is absorbed.
Meanwhile, cut the butternut squash in half vertically, keeping the peel on, and seed it removing all of the stringy parts. Then, cut the squash horizontally into 6mm (1/4 inch) slices. Set aside.
Line a large clay pot, or other large roasting dish that has a cover, with parchment paper. Place half of the couscous mixture in the bottom of the pan, patting it down to make sure you have an even layer, and then add a layer of butternut squash slices. Add all of the chicken on top of the butternut squash, and then layer with rest of the butternut squash. Place the rest of the couscous mixture on top and add the remaining 1/2 cup of water. Place a piece of parchment paper on top of the pan and cover tightly with the lid.
Place in the oven and cook overnight or for 4 hours at the higher temperature. Invert on a platter for presentation.