Preheat the oven to 200°C.
Pulse flour and butter in a food processor until the mixture looks like breadcrumbs.
Add the egg and pulse until a soft dough forms.
Roll the dough on a floured surface to 0.5cm thickness and trim edges.
Place dough on a floured baking sheet and bake for 8 to 10 minutes until golden.
Melt butter and caster sugar together in a small non-stick frying pan.
Cook mango in the pan for 2 to 3 minutes until caramelised.
Whip cream and icing sugar in a bowl until soft peaks form.
Arrange mango slices on the pastry and drizzle with pan juices.
Cut the tart into wedges and serve with Chantilly cream.