On Noche Buena (Christmas Eve) in Spain and Latin America, a cheerfully jiggling flan is nearly always present. In these places, flan is made so often that many cooks don’t need a recipe. Sofia Perez, a food writer in New York, explained how her mother, who is from Spain, does it for Christmas: For every person at the table, use one egg and one tablespoon of sugar. Break the eggs; every time you accumulate eight, add one extra yolk. Measure the total amount of egg in cups, then add the same amount of whole milk. Add the sugar and whisk (she doesn’t bother with scalding the milk or heating the custard), pour into a caramel-coated pan, and bake.

The differences among flans are all about the proportions of egg yolks to egg whites to dairy. Egg whites make flan firmer and bouncier; egg yolks make it richer and softer. Whole milk provides a different mouthfeel from cream. Fany Gerson, the Mexican-American pastry chef and author of “My Sweet Mexico,” uses egg yolks and half-and-half in her flan a la Antigua.

Ms. Button, whose recipe I adapted because of its simplicity, hit on a formula of six eggs plus two extra yolks that produces an ideal texture (though one yolk more or less would be fine, too). Another benefit is that her home-cook-friendly recipe uses a basic loaf pan; a tube pan and a Bundt pan also worked well. I did not want to mess around with ramekins or custard cups. Cooking in a water bath is delicate enough with just one baking dish, never mind six.

Then there is the caramel.

“Caramel is a source of extreme anxiety,” Ms. Button said. Unnecessarily so, in her view. Modern American cooks seem to be equally afraid of crystallizing sugar, burning the caramel and burning themselves. She recommends starting with a “wet” caramel, which has a little water added to the sugar that quickly turns it into a clear syrup as the cooking begins.