Preheat the oven to 200C/400F/Gas 6.
For the pastry, place the flour, sugar and butter into a food processor. Pulse until the mixture resembles breadcrumbs.
Add the egg yolk and pulse until the mixture comes together as a dough.
Turn the dough out onto a lightly floured surface and roll out to make a round slightly larger than a small ovenproof frying pan.
For the filling, heat the butter in a small ovenproof frying pan. Add the brown sugar and mango slices and fry until the mango is just starting to caramelise. Squeeze in the lime juice and remove from the heat.
Place the pastry over the mango in the pan and push down around the edges to seal in the filling.
Transfer the pan to the oven and bake for 12-15 minutes, or until the pastry is golden-brown and crisp.
Carefully turn the tart out onto a plate so that the mango is on top and slice into wedges. Serve with double cream.