For the panna cotta, soak gelatine in cold water. Cut the vanilla pod lengthwise and scrape out the pulp. Bring the cream, 2 tablespoons of sugar, vanilla pulp and vanilla pod to the boil in a saucepan. Simmer for about 5 minutes, remove from heat and cook for about
Leave to cool for 5 minutes. Remove vanilla pod. Squeeze the gelatine, dissolve in the hot cream. Pour into a rectangular mould (approx. 1 l capacity) or four small moulds (each containing approx. 250 ml).
Chill for at least 4 hours, preferably overnight.
Bring half frozen blueberries and 2 tablespoons of sugar to the boil. Simmer for about 5 minutes, then pass through a fine sieve and collect the juice. Stir starch and 2 tbsp. cold water until smooth. Bring blueberry juice to the boil and stir in the starch.
Simmer the rest of the blueberries for 2-3 minutes. Season to taste with sugar.
Turn out the panna cotta from the mould and cut into slices. Arrange on the blueberry compote. Serve with vanilla ice cream.