Artisan Loaf

Four extra tiles of crafting reach in every direction sounds minor until you have a workshop. It means the anvil, the furnace, the loom and the alchemy table can all sit inside one standing spot instead of making you shuffle between stations for every recipe, and the effect follows that character into every world forever.

The catch is the seller. The Skeleton Merchant only turns up underground, at random, and only stocks the loaf on three of the moon phases, so the window is narrow. When you find him with it listed, buy it right then instead of planning to come back.

One per character, permanently. After you eat it he stops offering it, so there is nothing to farm and no reason to save gold for a second.