All the recipes in this book were made using unsalted butter unless otherwise specified, and they were tested with Land O’Lakes butter, a fine-quality butter that is available throughout the United States. However, if you have a local creamery that makes butter, I’d suggest you use it. And if, by chance, you can get cultured butter, I’d urge you to use it, especially if you’re baking — you’ll get a flavor that will come much closer to the flavors of French butter. Unlike “regular” butter, cultured butter is made from cream that has been fermented, or cultured, for several hours, often for as long as 18 hours, before it is churned (a lactic culture, like that used for yogurt, is added to the cream). The result is a butter with a slight tang. Not all French butters are cultured — only the best ones, and often the ones that have an AOC (such as butters from Charentes, Isigny, or Echiré). Culturing accounts for one of the significant French-American differences in butter; the other is the higher percentage of butterfat in French butters. By law, American butters must contain at least 80 percent butterfat; in France, the minimum in 82 percent, and the great AOC butters usually have at least 84 percent. The more butterfat, the more flavor, and the less water. At home in America, I get the quality of small-batch churning, the flavor of culturing, and a high butterfat content from Vermont Butter & Cheese Company’s and Straus Family Farm’s (California) butters.