Combine peach, sugar and vanilla in a large bowl. Set aside for 5 mins or until peach releases its juice. Melt butter in a large non-stick frying pan over high heat. Add peach mixture and cinnamon. Cook, tossing gently, for 4 mins or until peach begins to soften. Add maple syrup. Cook for 1 min or until syrup thickens slightly. Set aside to cool. Discard cinnamon.
Grease a 7cm-deep, 10cm x 20cm (base measurement) loaf pan and line the base and sides with baking paper, allowing the sides to overhang.
Cut 1 cake layer into a 10cm x 20cm rectangle. Place in the prepared pan. Reserve half the peach mixture in a bowl. Cover and place in the fridge. Place the remaining peach mixture in a bowl. Lightly crush with a fork.
Spoon one-third of the ice cream over the cake in the pan. Drizzle over one-third of the crushed peach mixture and swirl to marble. Sprinkle with one-third of the granola. Repeat layering with remaining ice cream, crushed peach mixture and granola.
Top with the remaining cake layer, trimming to fit. Place in the freezer for 4 hours or until set.
Place the reserved peach mixture in a small saucepan over low heat. Stir until heated through. Invert cake onto a serving platter. Top with peach mixture and extra granola. Dust with icing sugar.