Thoroughly rinse the potatoes and courgettes and finely slice without peeling them.
Peel onions, halve and cut into thin slices. Peel and chop the garlic clove.
Melt a tbsp. of margarine in a pan and fry half of the onions and the garlic until slightly golden brown. Preheat the oven to 220°C/428 °F fan
Mix fried onion and garlic, silken tofu, cashew paste/butter, hot mustard, yeast flakes, a pinch of nutmeg, a big dash of salt, pepper and herbs of Provence in your blender.
Brush the mould with olive oil. Spread 3 tablespoons of the tofu sauce over the bottom of the mould. Mix the potato and zucchini/courgette slices and the remaining onion slices, add some salt and fill into the dish. Note: You can, of course, layer the potato and zucchini/courgette slices neatly and fan-shaped into the mould. I'm a little lazy though :-) and just put the mingled slices into the mould and press them a bit flat.
Sprinkle the ingredients with a pinch of nutmeg, a pinch of salt, pepper and add a few margarine flakes. Pour the rest of the tofu sauce over the ingredients.
Bake the gratin in the preheated oven at 220°C/428 °F fan for about 25-30 minutes until golden brown.
Cut the chives. Remove the gratin from the oven and serve hot, garnished with plenty of chives. Enjoy