Many people celebrate winter holidays with a glass of bubbly, but what happens when the party\u2019s over and they\u2019re stuck with a bunch of open bottles? Beverage directors across the country are infusing, reducing or freezing flat bubbles.\r\n\r\n\r\nJust Add Aromatics\r\nAt New York City\u2019s Union Square Caf\u00e9, flat Champagne becomes a vermouth, showcased best in the restaurant\u2019s House Martini.\r\n\r\n\u201cWe have a very strong private-dining business,\u201d says Beverage Manager Ryan Chavis. \u201cEvery now and then, we would have leftover Champagne from a party.\u201d\r\n\r\nIn keeping with the restaurant\u2019s mission to reduce waste, he allows the bottles to \u201crest\u201d overnight until the carbonation subsides. He then infuses the wine and adds a neutral spirit so that it lasts several weeks (recipe below).\r\n\r\nThe end result is a blanc vermouth with apple and honey notes, which Chavis mixes with Neversink, a New York gin distilled from apples.\r\nHot, Cold or Re-fermented\r\nAt Los Angeles\u2019s Bar Clacson, co-proprietor Eric Alperin brews a nuanced \u201cChampagne syrup\u201d to sweeten an Aperol Spritz variation that dissolves equal parts sugar and flat bubbly over gentle heat.\r\n\r\nYou can also freeze once-sparkling wine into ice cubes for sangria or highball-style cocktails. Be advised, however, they melt relatively quickly since there\u2019s still some lingering alcohol.\r\n\r\nAnother option is to allow the flat wine to ferment into a rustic Champagne vinegar. Chavis has tried this to much success, too, and likes to macerate the vinegar with fresh fruit to make shrubs.\r\n\u201cFlat Champagne\u201d Vermouth\r\nThis stovetop vermouth recipe can be adapted easily, depending on which botanicals you choose to flavor the vermouth. There\u2019s no hard-and-fast rule. Chavis says, \u201cDo it to taste.\u201d He does, however, suggest a light hand on the spices, and especially the bittering agents.\r\n\r\nCourtesy Ryan Chavis, beverage manager, Union Square Caf\u00e9, New York City\r\n\r\nIn doubled freezer bags, combine 2 bottles flat Champagne with 2 grams of cinnamon, coriander and/or cardamom; 5 grams orange or lemon peels; 1-2 grams bittering agents like gentian; 1 cup sugar; and about 1 cup vodka or brandy.\r\n\r\nBring pot of water to 130\u02daF. Add Champagne mixture. Infuse for 1 hour, massaging bags every 15 minutes to break down sugars.\r\n\r\nRemove bags from heat. Strain and cool to room temperature. Transfer to bottles. Refrigerate for up to 6 weeks.