prepare a baking sheet and squash
Arrange a rack in the middle of the oven, then preheat it to 220 °C / 430°F. Line a large baking sheet with parchment paper. Optionally (depending on which squash you use) peel the squash. Using a spoon, remove the seeds and cut into 1 cm (1/2 inch) thick slices.
make the harissa oil
Add harissa, coriander seeds, and cumin seeds to a skillet. Place over medium heat for a couple of seconds, or until the spices start to develop amazing aromas. Remove from the heat and transfer to a bowl. Add olive oil and canola oil. Season with a pinch of salt and a pinch of pepper, and stir to combine. Drizzle two tablespoons of harissa oil over the squash and toss to combine. Spread the squash in a single layer on a baking sheet.
roast the squash and chickpeas
Place the baking sheet with the squash into the preheated oven. Roast for 10 minutes at 220 °C / 430°F. Spread cooked (or canned) chickpeas over the paper towels and pat dry. Transfer to a bowl and add a tablespoon of homemade harissa oil. Remove the roasted squash from the oven and using a kitchen spatula or a spoon push the squash to one side of the baking sheet. Place the chickpeas on the empty side of the baking sheet. Place back in the oven and continue to roast for 10 - 15 minutes at 220 °C / 430°F, or until the squash is soft and baked, and the chickpeas are golden-brown and slightly crunchy.
While the squash and chickpeas are roasting prepare the yogurt cream. In a bowl, stir to combine tahini, diced garlic, olive oil, and freshly grated lemon zest. Season to taste with salt and pepper and stir to combine. Set aside until needed.
Remove the roasted squash and chickpeas from the oven. Set aside for 5 - 10 minutes to cool slightly. Spread the yogurt cream over a serving platter or plate. Place the roasted squash on top of the yogurt cream and sprinkle with roasted chickpeas. Optionally add 1/2 teaspoon of freshly grated lemon zest, sprinkle with chopped parsley and/or fleur de sel, and drizzle with the rest of that amazing homemade harissa oil. Serve warm or at room temperature.