Soak the gelatine in cold water. Whip the cream. Put the juice of half a lemon in a mixing bowl. Add the powdered sugar and a little bit of the buttermilk and stir until smooth. Only then stir in the rest of the buttermilk. Dissolve the gelatine and stir into the buttermilk mixture according to the instructions on the packet. Quickly fold in the whipped cream and chill for several hours.
Shortly before consumption, puree the selected (or defrosted frozen) strawberries with the brown sugar and spread on the buttermich cream that has now set. When serving, both components mix together - very delicate!