Preheat oven to 400˚F.
Place chickpeas, oil, cumin, salt, and pepper into a mixing bowl and toss together. Spread in a single layer, onto a parchment-lined baking sheet and roast on the lower oven rack for about 20 minutes, shaking the baking sheet occasionally to avoid sticking.
Remove from oven and set aside until ready to use.
Place prepared sweet potatoes directly onto the top oven rack and roast until tender, 40-50 minutes (this should be done at the same time the chickpeas are put in the oven).
While the chickpeas and sweet potatoes are roasting, drain cashews and place in a blender with remaining ingredients. Blend on high until sauce is completely smooth, about 2 to 5 minutes depending on blender. Generously season with salt and pepper and pulse a few times to fully incorporate seasonings.
To serve: Split each sweet potato down the center and scoop chickpeas into each sweet potato. Drizzle each with the cashew sauce and serve, with more sauce on the side.