Beat yolks and 2 cups sugar until light yellow and fluffy. Gradually beat in brandy, sour mash and 4 quarts cream. Beat whites in separate bowl until they hold soft peaks. Beat in 2 cups sugar, about a tablespoon-full at a time. Beat until very firm. Fold egg whites into remaining cream. Stir lightly into liquor mixture. Allow eggnog to stand in a cool place for 6 to 12 hours. A stoneware crock is ideal. Serve eggnog sprinkled with fresh grated nutmeg. Makes about 12 quarts.
Serve left-over sour mash and single malts to them as don't cotton to eggnog.