Advance preparation

The sauce will keep for up to 2 days in a covered container in the refrigerator; bring to room temperature for serving. The croquette mixture will keep for up to 1 day in a covered container in the refrigerator. To serve warm, sauté the croquettes just before serving or make them up to 1 day in advance, cover and refrigerate, and reheat on a baking sheet in a 350°F oven for about 5 minutes.