Mushroom Sauce (white)

• ¼ cup butter
• ¼ pound mushrooms, sliced
• ½ small

Melt the butter in a saucepan. Add the mushrooms and onion and sauté until the mushrooms are tender. Blend the flour with the milk and add to the saucepan. Cook over low heat, stirring constantly, until thickened. Add salt and pepper.