For the sauce, place the fresh cherries, cinnamon, vanilla, kirsch and sugar in a small bowl and leave to poach until soft. Remove the cherries from the liquid and take out their stones, reserving the poaching liquor and three cherries with stalks on for the garnish.
Blitz half of the cherries in a food processor or blender and press the mixture through a sieve. Stir in a little of the poaching liquor until it is the consistency of a sauce. Set aside.
For the soufflé, preheat the oven to 200C/180C Fan/Gas 4. Grease a baking dish with the butter. Line with baking paper and spoon in the remaining cherries and the sour cherries
Heat the milk with the vanilla pod, semolina and 65g/2¼oz of the caster sugar. Cook for 10 minutes, or until the mixture has thickened.
Whisk the egg whites with the remaining sugar and the lemon juice until it forms stiff peaks.
Stir the eggs yolks into the semolina mixture and stir in a third of the egg whites. Carefully fold in the rest of the egg whites and spoon into the baking dish. Dot the reserved cherries with stalks on top and bake for 20–25 minutes.
Remove from the oven and dust with icing sugar. Pour over the cherry sauce and serve immediately.