Preheat the oven to 375 degrees F. Prick the sweet potatoes with a fork and roast for 45-55 minutes until they are just tender. Let the sweet potatoes cool for 5-10 minutes before halving them lengthwise and fluffing their flesh with a fork.
While the sweet potatoes are roasting, make the crispy chickpeas. Drain and rinse the chickpeas. Pat them dry with paper towels. Remove any loose outer skins. In a small bowl, toss the chickpeas with 1/2 tablespoon olive oil, 1/2 teaspoon kosher salt, 1/4 teaspoon black pepper and cumin. Spread them in a single layer on a parchment paper-lined sheet pan. Bake for 25 – 35 minutes until crisp and browned, gently shaking the pan about halfway through cooking.
While the sweet potatoes and chickpeas are roasting, heat the remaining olive oil in a large skillet over medium high heat. Sauté the spinach until the leaves start to wilt, about 2 minutes. Add the garlic and remaining salt and pepper, and continue cooking until fragrant, about 1 minute.
Top each of the sweet potato halves with chickpeas and spinach. Drizzle with tahini and sprinkle with flaky sea salt and red pepper flakes before serving.