Grease a baking tray and palette knife with oil or butter.
Heat sugar in a heavy pan over moderate heat without stirring until melted.
Swirl the pan as the sugar turns a light hazelnut brown.
Remove from heat, stir in the almonds immediately, and pour onto the tray.
Smooth with the buttered knife and let cool for 30 minutes before chopping.
Boil the maple syrup in a heavy pan over high heat.
Whisk the egg white with salt until firm peaks form.
Pour boiling syrup into the egg white slowly while whisking constantly.
Whisk for 10 minutes until thick and stiff, then cool for 20 minutes.
Whisk double cream until it holds its shape and fold it into the meringue.
Fold in the chopped praline and spoon into lined moulds or a loaf tin.
Freeze for 4 hours and soften in the fridge for 20 minutes before serving.