Put all ingredients, but only half of the grated lemon zest, in a saucepan and stir well. Bring to the boil, stirring constantly, and continue cooking until the cream thickens.
Put in a mold and let it solidify in the refrigerator, which takes at least 8 hours. Then turn out on a platter, decorate with the remaining lemon zest and serve.
The cream can also be served in portions in serving bowls. So it doesn`t have to be overturned and can be served faster.