Cupcakes are far from diet food, but if you're going to indulge, you want the moistest, most delicious cupcakes you can make. Moist cupcakes start with emulsifying ingredients -- whole eggs, healthful oils, vegetable purees and sugar. How you mix and bake the cupcakes can also make a difference in how moist they are. Cupcakes continue to bake for a minute or two after you remove them from the oven, so pull them out when they're slightly underdone to keep them moist.
Ditch the Butter
Most traditional cupcake recipes call for butter to be creamed with sugar. This process causes tiny pockets of air to form in the batter. These pockets fill with steam as the cupcakes bake, ensuring light, moist cupcakes. But if you opt for dense, fruit cupcakes, such as applesauce, banana, pumpkin or carrot cupcakes, the fruit purees add moisture without the need for aerating the butter. Forget the butter entirely and use a light olive oil instead. Use an olive oil with little taste, rather than a robust extra-virgin olive oil, to avoid overwhelming the delicate taste of cupcakes.
Don't Skimp on Emulsifiers
Baking cupcakes is part art, but mostly science. Each ingredient plays an important role in the chemistry of the cupcakes. Flour and egg whites provide structure to cupcakes, while egg yolks, sugar and fat help tenderize them. Although it might be tempting to use egg whites instead of egg yolks or cut out the oil, doing so will leave you with dry cupcakes. Use whole eggs or even add an additional egg yolk. If you cut back the oil, compensate by adding some applesauce or sour cream. Even adding a little bit more sugar can add moisture to cupcakes.
Mix It Up
Another trick to making moist cupcakes is to mix them with a light hand. When you over-mix cakes or quick breads, you encourage gluten development. Gluten is a welcome addition to chewy yeast breads, but absolutely taboo when it comes to tender, moist cupcakes. Beat all the wet ingredients together first. Then sift the dry ingredients in a separate bowl. Mix the wet ingredients with the dry ingredients only until they're completely combined, then stop.
One of the most common reasons cupcakes are dry is because they were over-baked. Try baking cupcakes at 325 degrees Fahrenheit for 20 to 28 minutes. Set your timer for five minutes before you think they'll be done. Insert a toothpick in the cupcakes. If the toothpick comes out with just a few moist crumbs, the cupcakes are done. It's better to slightly undercook them than overcook them. Keep the oven door closed during the first 20 minutes of cooking. Opening the door causes the temperature to drop and may result in hard, flat cupcakes. Make the cupcakes the day before you plan to serve them. Cool and frost them and store them in a covered container. As they sit, some of the moisture in the frosting will transfer to the cupcakes.