1. Preheat the oven to 110ᵒC (fan-assisted).
2. Grind the Ricola Herbal Caramel drops with the pestle and mortar, place in a small saucepan along with the heavy cream and slowly bring to the boil.
3. Place the egg yolk, sugar and salt in a bowl and whisk thoroughly.
4. The herb drops should now have completely dissolved in the boiled heavy cream. If they have not, remove the pan from the stove and leave to stand for a few minutes. Then bring to the boil again while stirring constantly until all the pieces have dissolved.
5. Gradually add the boiled mixture to the mixture of egg yolk and sugar while stirring and mix well.
6. Quickly pour the mixture into four oven-proof clay pots or small bowls and let them set in the oven at 110ᵒC for 30-40 minutes, depending on the moulds.
7. Remove the dishes from the oven and refrigerate until serving.
8. Before eating, sprinkle the caramelizing sugar on the surface of the custard. Caramelize the sugar by placing it under the grill at the highest setting for 3-5 minutes and then serve.