In a saucepan with a thick bottom to put the juice, zest and 120 g of sugar, stir and bring to boil.

In parallel in a large container whisk the eggs and 120 g sugar.

In the egg mixture in a thin stream, stirring constantly, to enter 1/3 part of the hot juice. This hardening process. Place the saucepan with the remaining juice on a slow fire, and a thin trickle, stirring constantly, to enter the tempered egg mixture. Continue to cook over very low heat and, stirring constantly, until thick honey and the characteristic gurgling. Strain the cream through a sieve and add 2-3 drops of essential oil of bergamot (optional). To cool the cream to 50"C.

Then enter the pieces of soft butter and a very good whisk.

This delicious cream to fill eclairs or Shu, to make it a layer in any cake, serve with ice cream, but you can eat with a spoon!