1. Boil water with half of the crumbled bouillon for the crozets.
2. Cut the leeks into thin slices and the cured ham into pieces.
3. Melt the butter and oil in a saucepan and add the leeks.
4. Preheat the oven to 180°C (350°F).
5. When the water is boiling, add the crozets and cook for the time indicated on the package.
6. Once the leeks are tender, add the mustard and flour, as well as the other half of the crumbled bouillon.
Mix everything together, then add water and mix again.
7. Let it simmer on low heat for the cooking time of the crozets.
8. Once cooked, drain the crozets and add them to the saucepan with the leeks, mix everything together.
9. Pour half of the mixture into a gratin dish, arrange the cured ham and add the remaining crozets on top.
Sprinkle with grated Comté cheese and bake for 15 minutes.