Put butter and sliced pumpkin in a saucepan, sauté for 5 minutes, then add sugar
Continue stirring, add cinnamon and lemon peel, pour in 30 ml water, simmer 10 minutes, then rest for at least 30 minutes
Preheat oven to 180°
Cut puff pastry into desired shape, preferably round using a pastry ring
Place pastry on baking sheet with greaseproof paper, add sautéed pumpkin, and bake for 15 minutes
Remove, cool, top with vanilla ice cream, and serve