Preparation:

1. Put a frying pan on the heat without oil with the mushrooms and a pinch of salt.
2. Add 3 tablespoons of extra virgin olive oil, the onion and fry for 5 minutes.
3. Add the flour and cook, stirring constantly, for 3-4 minutes. Lower the heat and pour in the previously heated oat drink with some salt and pepper. Stir, while it thickens and in 7-8 minutes it will be ready.
4. Wash the asparagus and put them on a tray. Cover themn with the mushroom bechamel sauce.
5. (optional) Add cheese on top.
6. Bake for 10 minutes at 200ºC and grill for 3-4 minutes in the upper part of the oven.