Melt butter in a saucepan, then add the flour. Stir continuously until a paste forms – this is called a roux. Keep cooking for 2 mins.
Add the milk to the roux gradually, stirring as you go, until you get a smooth sauce. Cook for 5-10 mins, stirring continuously, until the sauce has thickened. Season to taste with salt and pepper.
Once cool add spring onion, crab and spring onion and combine
Butter two pieces of sliced pan. Turn them over and fill the with the crab bechemal mix. Add a layer of crunchy thinly sliced red cabbage
Heat a pan over medium hot heat, fry the sandwich til it’s golden brown. Flip it over and fry the other side