1. Cut the eggs in slices and place in an oven dish.
2. In a saucepan melt the butter and add the onions. Cook until soft 45 minutes. Add the flour stirring with a wooden spoon. Add the milk, salt and pepper. Reduce the heat and cook the sauce for some minutes. Pour the sauce over the eggs.
3. Sprinkle with the cheese and bake ,in a 400ยบ oven, 10-20 minutes until nicely brown.