Using the slicer, cut the celeriac into thin slices.
Mix the egg and Cream together.
Season to taste with salt and pepper.
Put a layer of celeriac in a greased oven dish lined with baking paper and spread the egg mixture on top.
Grate cheese and truffle over it.
Repeat until the mould is full or the celeriac is finished.
Bake in the oven at 165°C for 40 minutes.
Cool down and put aside under pressure.
When cooled, cut into nice even slices.