1Preheat the oven to 425°F.
2Wrap each half of sweet potato in aluminum foil, place them on a cooking sheet and put them in the oven for about 45 minutes or until fork tender.
3Once the sweet potatoes are cooked and slightly cooled, lightly carve the interior (the puréed flesh will be mixed with the chick peas).
4In a bowl, mix the chick peas with garlic and spices so they are well coated.
5Place the chick peas on a cooking sheet and put in the oven for 25 minutes, stirring them every now and then. In a bowl, mix the chick peas, mashed sweet potatoes, diced avocado, chopped parsley and a drizzle of olive oil.
6In a bowl, mix the plain yogurt, cumin, olive oil, salt and pepper.
7Fill the sweet potato halves with the chick pea mix and top generously with yogurt sauce.