Use a fork to pierce the sweet potatoes. Drizzle a little olive oil over the sweet potatoes and rub it into the skins, then rub a little salt on them. Put the potatoes in the roasting tin (halve if they're too big) and roast for 40-45 minutes until soft and tender.
Mix tahini, chili crisp, a little salt and lemon juice. Add a little water to reach a viscous pouring consistency.
Fry garlic in olive oil until it just starts to brown. Add the cannellini beans and stir for 2-3 minutes to cook through. Add the spinach to the pan and stir for 1 minute until quite wilted. Add the chill crisp and stir to combine.
Serve potatoes halved, with spinach cannellini on top, drizzled with the sauce.