To make the baked bananas: Pre-heat the oven at 190˚C. Line a baking tray with parchment paper. Place a piece of popiah pastry on a flat plate. Put a banana on one of the corners of the square pastry. Wrap up the banana with the pastry and ensure the ends are tucked in. Arrange the wrapped bananas on the baking tray and brush the top of the pastry with some butter. Sprinkle with some sesame seeds. Bake the bananas in the oven for 10-15 minutes, or until they turn golden brown.