Rúgbrauð is an Icelandic straight rye bread, dark and dense, usually rather sweet, traditionally baked in a pot or steamed in special wooden casks by burying it in the ground near a hot spring. Modern rúgbrauð is usually made in a square baking pan. The bread is crustless, dark and very dense and keeps for a long time. It is often served with butter, mutton paté, hangikjöt (smoked lamb), or with pickled herring. Dry rúgbrauð would be ground and mixed with buttermilk to form a kind of porridge. Stale rúgbrauð is often soaked, then made into brauðsúpa (bread soup) - that is, simmered with raisins and flavorings (usually lemon) and served hot with whipped cream as a dessert.