melt 3 tablespoons of butter in the pan. 

add 3 tablespoons of white flour and stir well. stir

add milk (I prefer cream), a little at a time, keep on stirring till you have a smooth white sauce. 

add salt and white pepper. In Denmark They add a little touch of curry powder.

add the fishballs and warm it all. 

Serve with potatos and vegetables, you may use raw grated carrots, radish, any Julian vegetable with a little bit of sugar and lemon juice.

ENJOY