Clean and parboil a sweetbread and cut in cubes. Melt two tablespoons butter, add three tablespoons flour, and pour on gradually one cup chicken stock. Reheat sweetbread in sauce and add one-fourth cup heavy cream and one and one-half teaspoons beef extract. Season with salt, paprika, and lemon juice. Fill ramequin dishes, cover with buttered crumbs, and bake until crumbs are brown.