Put the cream and milk in a bowl, drizzle in the sugar and stir well until it has dissolved. Grate the tonka bean with a nutmeg grater. Add to the cream with the egg yolks and stir again. The mixture can now rest a little, but it should be at least 30 minutes.
Preheat the oven to 150 degrees, stir the mixture briefly again and pour it into refractory molds. The grated tonka bean likes to stick to the bottom of the bowl, loosen it with a spoon and carefully stir the bowls again.
Fill a baking dish with boiling water, place the bowls in it and let everything set in the oven for about 50 minutes. Remove the bowls, let them cool down completely and cover them in the refrigerator for about 6 hours to set.
To serve, remove from the refrigerator, immediately sprinkle with sugar and caramelize with a burner.