To make the toffee sauce, put the sugar in a deep saucepan with 75ml (3fl oz) water. Stir over a low heat until the sugar dissolves.
Turn the heat up and let the syrup bubble away. Carefully swirl the pan to ensure it cooks evenly but don’t stir. When the caramel has turned a rich amber colour, carefully pour the cream into the pan (it will splutter) and remove from the heat. Stir gently with a spoon to mix the sauce and add a pinch of salt. Allow to cool slightly.
Meanwhile, toast the nuts in a dry pan until golden and fragrant. Set aside to cool.
Slice the mangoes lengthways, running the knife along either side of the flat stone, to cut off 2 fat cheeks per fruit. (The flesh left clinging to the stone can be eaten.) Sprinkle the surface of each mango cheek with ½tsp sugar, then cook, sugared-side down, for 4-5 minutes, until soft and juicy with lightly charred lines. Serve the cooked mango cheeks with some vanilla ice cream, a drizzle of toffee sauce and top with the toasted pecans.
Tip Store ice cream in a Thermos flask to keep it frozen until you need it. The toffee sauce will keep well in the fridge for up to 5 days. Just keep it chilled until needed.