Wrap the entire terrine in film and cook in a bain-marie. Cook in a non-preheated oven at 75°C for approximately 1 hr 45 min (check that the temperature is 62°C in the middle).
Take out of the oven and remove the film and lid. Place in the refrigerator.
The next day, replace the lid.
Wait at least three days before eating. Remove from the terrine and slice with a knife dipped in hot water.
Grind cinnamon over the slices (season to taste).