Ingredients (for 2 servings):
1 tbsp butter
1 1/2 tbsp all purpose flour
250 ml (1 generous cup) milk
2-4 tsp mustard (Dijon or your preferred kind)
Boil eggs 5 minutes (or shorter/longer for softer/harder eggs). For the sauce, melt butter over medium heat. Add flour and cook for about 2 minutes, stirring constantly. Keep stirring and slowly add milk. Stir well to dissolve the flour/butter mix in the milk. Reduce heat to low and - still stirring! - bring milk to a boil. Let simmer (stirring!) for 1 minutes. Remove from heat and season to taste with mustard, salt, and pepper. Peel eggs, cut in half and serve with the sauce, boiled or mashed potatoes, and a side salad (e.g. Swedish Cabbage and Apple Salad).
(adapted from: "Dänisch kochen" by Charlotte Noer)