Delicately pink and deliciously flavored. Unlike the butters above, which are generally used as a sauce or condiment, shellfish butter is primarily used as a last-minute addition to sauces to be served with fish or shellfish (sometimes the very same creatures used to make the butter).

Spread on a baking sheet and dry in a 250°F oven for 30 minutes:

When cooled, place the shells in a towel, fold the towel over, and break them up as fine as possible with a mallet or rolling pin. Melt in the top of a double boiler over simmering water:

Add the shells and cook over the simmering water for 10 minutes. Set aside for 20 minutes to allow the flavors to infuse. Pour into a fine-mesh sieve set over a bowl; let stand for up to 20 minutes to drain off all the butter. Refrigerate until chilled. Skim off the butter when the mixture has solidified; discard any liquid.

Use immediately, or let the butter soften and roll, chill, and store as directed.