Peel the apples, cut into 5 mm-thick wedges and place in a microwave-safe dish. Sprinkle apples with lemon juice and microwave until tender.
Soak grapes in rum to soften.
Cut sponge cake into 3 cm cubes, place in a bowl, add steps 1, 2, maple syrup, melted butter and cinnamon, and mix. Let stand until sponge cake is soaked.
Lay out the egg roll sheets and place half of step 3 horizontally in the center. Fold the remaining sheet over the filling. Repeat with the other sheet.
Place a sheet of parchment paper on a baking sheet and place step 4 on the sheet, folded sides up. Brush with egg wash and bake at 220℃, until golden brown.
