Gently rinse the elderflower heads to remove any insects and dirt.

Cut off the stems, leaving only the flowers. Set the flowers aside.

In a mixer, whisk the egg yolks, sugar, and vanilla sugar together for about 2 minutes until the mixture is light and fluffy.

Pour the heavy cream, whole milk, and elderflowers into a saucepan.

Heat gently to 80°C (176°F) over medium heat, stirring occasionally. Use a thermometer to ensure the temperature does not exceed 80°C (176°F).

Strain out the elderflowers and discard them.

Clean the saucepan, then pour the warm milk mixture back into the pan.

Add the egg mixture to the milk mixture while stirring.

Heat gently again to 80°C (176°F) without boiling. Stir constantly to prevent the mixture from separating.

When the mixture reaches 80°C (176°F), remove the saucepan from the heat.

Allow the saucepan to cool at room temperature for about 30 minutes.

Cover the saucepan and place it in the refrigerator for at least 3 hours, or overnight.

Remove the chilled ice cream mixture from the refrigerator.

Pour the mixture into an ice cream maker and process for about 15-20 minutes, or until the ice cream has a creamy consistency. The time may vary depending on the type of ice cream maker.

When the ice cream is ready, it can be served immediately as soft ice cream, or transferred to a freezer-safe container and frozen for a few hours for a firmer consistency.

Store any leftovers in the freezer in an airtight container.