The day before. Heat the milk and cream in a saucepan with the heads of elderflowers, until slightly simmering. Turn off the heat and let it cool down slightly.
Beat the egg yolks with the sugar until light and pale, then add a tablespoon of honey.
Sieve the milk and cream and pour slowly in a thin stream into the egg yolks and stir constantly with a whisk to prevent the eggs from curdling.
Put the custard in a double boiler on the stove and heat till 83°C or mix with a whisk until it reaches the first boil. Turn off, cover with cling film and let it cool, then move it into the fridge until the next day.
The next day. Pour the custard into the chilled ice cream maker and follow the instructions.
When the gelato is ready, scoop it into a plastic or metal container and transfer it into the freezer for a few hours.
Remove from the fridge about 10 minutes before serving.