Combine sugar and yeast in a bowl. Stir in ¼ cup (60ml) warm water. Stir until combined. Add the banana and egg and whisk to combine.
Place the flour, mixed spice and cinnamon in a bowl. Use your fingertips to rub the butter into the flour mixture until it resembles fine breadcrumbs. Stir in the banana chips, mixed dried fruit and currants. Make a well in the centre. Pour in the banana mixture and stir with a wooden spoon until a dough forms. Turn onto a floured surface. Knead for 10-15 mins or until smooth and elastic (the dough should be sticky, so don’t use too much flour when kneading or it may become stiff and not rise properly). Place in a lightly greased bowl. Cover and set aside in a warm, draught-free place for 1 hour or until dough doubles in size.
Grease a 12 x 20cm (base measurement) loaf pan. Knead the dough on a lightly floured surface until it returns to original size. Divide into 8 portions and roll into balls. Place side by side in the prepared pan. Set aside in a draught-free place for 30 mins or until doubled in size.
Preheat oven to 200°C. Combine extra flour, extra sugar and ¼ cup (60ml) cold water in a bowl to form a smooth paste. Place in a sealable plastic bag. Cut off 1 corner. Pipe crosses onto buns. Bake for 10 mins. Reduce oven to 180°C and bake for 20-25 mins or until golden and loaf sounds hollow when tapped on top.
To make the glaze, stir gelatine, sugar and water in a bowl until dissolved.
Turn loaf onto a wire rack. Brush the top with glaze. Serve warm with butter.