Peel the potatoes, carrot and celery and cut them into 1 cm cubes. Peel the onion and cut it into fine strips.

Heat 1 tablespoon of butter in a frying pan and fry the onion strips over a medium heat until golden brown, then remove them and set aside.

For the sauce, melt the remaining two tablespoons of butter in the same pan, sprinkle the flour over it and cook briefly, stirring with a whisk. Add the milk and vegan cream whilst stirring, and allow everything to reduce to a creamy sauce.

Finely grate the cheese.

Whilst the sauce is reducing, cook the potatoes, carrot and celery in 7 dl of boiling salted water, uncovered, for 5 minutes until tender. Add the macaroni and cook until al dente, so that the liquid is just absorbed.

Add the vegetables and macaroni to the sauce, bring to the boil again and season with 1 teaspoon of salt, pepper and nutmeg.

Transfer everything to a greased gratin dish, sprinkle with the onion strips and the grated cheese. Bake in the oven at 220 degrees (top and bottom heat) for 10–15 minutes.