Pour the mushroom stock, cream and milk into a medium heavy-based saucepan. Sprinkle in the gellan and use a hand-held blender to combine completely. Bring the mushroom stock and cream mixture to the boil, simmer for 30 seconds, and then pass through a chinois into a tray. Leave to cool slightly and then refrigerate for 4 hours until set.
Break up the gel with a hand-held blender, trans