Scrub the beets lightly and boil them for 35 minutes until barely tender. Drain under cold water, peel, then slice into 1/4 inch pieces.
Melt the butter and cook the shallots for 4 minutes over medium heat. Turn the heat down and stir in the flour. Cook for 2 minutes stirring often. Add the stock, mustard and cream. Cook for a few minutes until thick.
Combine with the beets. Cook for a few minutes until it is warm. Add salt and pepper to taste. Serve with parsley sprinkled on top.