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Place the butter in a saucepan and heat until melted. Stir in a pinch of salt and taste the result. Add more spices if desired, or melt in more cheese if the flavor is too strong for you. Serve each person a slice of toast covered in a generous amount of Welsh rarebit. The mixture will be quite liquid, so provide knives and forks.
Melt butter over low heat. Taste test. Pour over the toast.