Cultured butter

Cultured butter is butter churned from cream that has first been ripened with lactic-acid bacteria, the way most of Europe has made it for centuries. That fermentation gives it a tangy, faintly cheesy depth and a heady buttery perfume that sweet-cream butter lacks, and the traditional beurre de baratte — churn butter — is the benchmark against which cooks measure a fine table and pastry fat.