Prick the sweet potatoes several times with a fork and place on a baking sheet. Roast for about an hour, until tender.
While the sweet potatoes cook, add the coconut oil to a large pan over medium-high heat. Stir in the onions and cook until they begin to soften, about 5 minutes. Add the garlic, ginger, garam masala, paprika, salt and pepper. Cook for about 1 more minute, stirring often. Add the tomato paste, canned tomatoes and chickpeas. Bring to a boil, then reduce heat and simmer for 25-30 minutes, stirring occasionally. Pour in the coconut milk and continue to simmer for 5 minutes more. Taste and adjust seasonings if needed.
To serve, slice open the sweet potatoes and scoop a healthy portion of the chana masala into each. Garnish the potatoes with the minced cilantro.