Mushroom potatoes can be made by members at level 64 Cooking by adding Mushroom and onion to a potato with butter. This does not require a range or fire and provides 55 Cooking experience, or 270.5 Cooking experience if the baked potato, pat of butter, potato with butter, sliced mushrooms, fried mushrooms, chopped onions, fried onions, and mushroom and onion are all made from scratch.
They are among the highest-single bite foods in the game healing 200 lifepoints each, or the same as sharks, but are 0.1 kg lighter than them. However, they sell at a 100 gp+ premium and it is far more difficult to obtain a mushroom potato on the Grand Exchange. Those few players who make potatoes tend to make tuna potatoes instead as they are higher healing, more profitable, and only require 6 stages of preparation rather than the 8 to prepare a mushroom potato. As such, most players tend to use the far more readily available shark instead for high end single-bite healing.