Preheat oven to 450°F and line a baking sheet with parchment paper. Drizzle the squash with olive oil and sprinkle with salt and pepper. Roast, cut side up, for 35 to 40 minutes, or until tender and browned around the edges.

Make the chimichurri: Place the pepitas in a food processor and process until finely ground. Transfer to a small bowl and mix in the red pepper flakes, garlic, cilantro, and several grinds of pepper. Add the lemon juice, olive oil, and maple syrup and stir until combined. Set aside.

Prepare the chickpeas: Heat the olive oil in a medium nonstick skillet over medium heat. Add the onion and a pinch of salt and cook until soft, 5 to 8 minutes, until browned, turning down the heat as needed. Turn the heat to low and add the garlic, cumin, cinnamon, and chickpeas. Stir to coat, then add the broth, 1/4 teaspoon salt, and several grinds of pepper and simmer for 5 minutes. Remove from the heat and stir in the lemon juice. Set aside for a few minutes to allow the mixture to thicken slightly. Stir in the cilantro just before assembling the dish.

Make the lemon yogurt: In a small bowl, stir together the yogurt, lemon juice, olive oil, and salt.

Place the squash quarters on a platter and top with the chickpeas and chimichurri. Garnish with cilantro and pepitas and top with the lemon yogurt.