Preheat the oven to 200C/400F/Gas 6.
Place the flour and butter in a food processor and pulse until the mixture resembles breadcrumbs.
Add the egg and pulse again until the mixture comes together to form a soft but not sticky dough.
Roll the dough out on a lightly floured surface to 0.5cm/¼in thick and trim the edges.
Place the dough onto a baking sheet dusted with flour and bake in the oven for 8-10 minutes, or until crisp and golden-brown.
For the mango, heat the butter and sugar together in a small non-stick frying pan until the sugar melts.
Add the mango and cook for 2-3 minutes, or until the mango is well coated and caramelised.
For the Chantilly cream, whip the cream and icing sugar together in a bowl until the cream forms soft peaks when the whisk is removed.
To assemble the tart, arrange the mango in overlapping slices on top of the cooked pastry and drizzle over any pan juices.
To serve, cut the tart into wedges and serve with a dollop of Chantilly cream.