Nuns at the Santa Clara convent in Puebla, Mexico, started making rompope in the 17th century. Though often called Mexican eggnog, this beverage is differentiated by its yellow hue, a result of cooked yolks and no egg whites. The Santa Clara sisters derived their recipe from ponche de huevo, or “egg punch,” which came to Mexico by way of Spain.

As officials from the Catholic Church ate and drank their way through Mexico’s religious houses, they encountered the velvety drink. Visitors lauded the rich mixture of milk, egg yolk, spices, sugar, and rum, and its popularity grew. According to local yolk lore, a Sister Eduviges made two key contributions to rompope enjoyment. First, she added a secret ingredient to her standout recipe, a special something that she never revealed. But perhaps more importantly, she successfully lobbied for the nuns to be allowed to enjoy their finished product.

Today, families prepare rompope during the holidays and liquor companies sell premixed bottles across the country. It’s a staple at Christmas, but it appears on other special occasions, as well. Across Latin America, drinkers often sip the festive beverage chilled or on ice, but Nicaraguans also enjoy a warm version. Creameries, bakeries, and restaurants use rompope to flavor ice cream, pastries, fruit, and cake batter. Some versions are thickened with almonds, chocolate, pistachios, walnuts, or pine nuts—the lattermost of which is often denoted by being dyed pink. It’s hardly a surprise that modern Mexicans of all classes and creeds have found a way to enjoy rompope in so many formats. Something so heavenly could only stay cloistered for so long.