Bacon with parsley sauce

3/4 kg un-smoked bacon
4 onions (if desired)
25 g butter
30 g flour
ca. 400 ml milk
salt
1 bundle parsley

1. The bacon should be cut into ? cm thick slices. Put the bacon on a hot frying pan and fry over an even heat until golden brown on both sides. Pour that fat into a cup as it is generated to make the bacon crispy. Season with salt when the bacon is hot. Alternatively the bacon can be fried in the oven at 200 C for about an hour.
2. If desired, the onions is fried in he bacon fat until golden brown.
3. Melt butter in pan and add flour. When the flour mix is hot and even, add the milk bit by bit until an even sauce has formed. Season with salt and add the chopped parsley. Just before serving, add a knob of cold butter.
4. Serve the bacon with the sauce, boiled potatoes and, if desired, the onions.