Preheat the oven to 204°C. Scrub the sweet potatoes and poke a few small holes in them with a fork. Arrange them on a large baking sheet. Bake the sweet potatoes for 45 minutes, or until they are soft on the inside.
In a medium saucepan over medium heat, combine the chicken, hot sauce and coconut milk. Simmer the mixture for 10 minutes to allow the flavours to combine and the sauce to slightly thicken.
Slice the cooked sweet potatoes down the middle to open them up. Scoop the Buffalo chicken into the sweet potatoes and top each serving with the ranch dressing, coriander (if using) and spring onions (if using). Serve the potatoes warm.