Preheat the oven to 200C/400F/Gas 6.
Bring a heavy-bottomed saucepan of water to the boil. Carefully lower the peaches, one at a time, into the boiling water using a slotted spoon, for 10 seconds then immerse immediately in bowl of cold water for one minute. Peel off the skins, halve and remove the stones.
Heat the butter and sugar together in an ovenproof saucepan over a medium heat, until the sugar has dissolved.
Add the peaches and lemon juice.
Add the champagne and using a match, carefully (have a saucepan lid ready in case it needs to be put over the flame) light the mixture, taking care to hold the pan at arm's length. Once lit, shake the pan gently, until the flame goes out.
Transfer the saucepan into the oven to cook for eight minutes. Using a spoon, regularly keep the peaches moist, by spooning over the juices in the saucepan.
To serve, arrange the peaches onto two serving plates and pour over the sauce from the saucepan. Sprinkle with the toasted almonds and serve with a scoop of the vanilla ice cream.