Place a pan on medium heat, add oil, half onions and garlic and stir fry until translucent, add vegetables, seasoning, cover and cook until just done. remove in a baking dish.
In the same pan, add 1/2 butter, once melted, add remaining onions and stir fry until translucent, add flour and mix well, until the flour starts smelling aromatic, about 2-3 minutes, turn heat to low and add milk and stock, stirring constantly until slightly thickened, turn heat off, stir in half the cheese, seasoning and continue stirring until well incorporated, check seasoning.
Preheat oven to 180 degrees celcius, pour the white sauce onto the vegetables, top with bread crumbs and remaining cheese and bake for 25 minutes. cool and serve with a side of salad or steak.
