Preheat the oven to gas 4 / 180C / 350F and grease a shallow ovenproof dish with some sunflower spread or butter
Make a roux in a small saucepan by melting the sunflower spread over a medium heat then mixing in the flour
Whisk in the stock a little at a time to avoid getting lumps in the sauce
Cook for 2 minutes until thickened
Meanwhile put a layer of potatoes in the bottom, slightly overlapping the slices as you go
Sprinkle some salt and pepper over then some sliced onion then pour over a third of the sauce mixture
Add another layer of potato, season with more salt and pepper and add onion on top as before, pour half of the remaining sauce over then add the final layer of sliced potato
Pour the remaining sauce over the top, you could add a sprinkle of paprika over if you like
Bake uncovered for 40 - 50 minutes until golden on top and the potatoes and onions are soft and cooked through
You can add in pre-cooked chopped ham or bacon for extra flavour, top with shredded cheese (Veganic brand is a great vegan no-soy choice), exchange the onion for leek, add in some peas or sweetcorn, dress it up however you like!
