Place the sugar and measured water in a heavy-based saucepan and bring to the boil. Continue to boil for 3–5 minutes until the syrup has reduced by half. Remove from the heat and stir in the yogurt and vanilla essence. Transfer to a freezerproof container and freeze for 3 hours.
Remove the ice from the freezer and beat with a wooden spoon until slushy. Freeze for a further 4 hours, or overnight, until firm.
Heat the butter in a large nonstick frying pan. Halve the bananas lengthways, then cut each of the halves in half again across its width. Sprinkle the bananas, cut side up, with the spice, if using, and cook in the hot butter for 30–60 seconds on each side until golden. Remove from the pan using a slotted spoon.
Pile the bananas on to serving plates in a lattice pattern, then drizzle with the maple syrup and scatter with the pecans. Serve with scoops of the vanilla yogurt ice on top.