From America's Test Kitchen Season 10: Old-Fashioned Fruit Desserts
Pineapple has become synonymous with upside-down cake ever since canned pineapple was introduced into this country in the early 1900s. But at one time, upside-down cakes were made with seasonal fruit, such as apples. We loved the idea of resurrecting apple upside-down cake. We wanted a rich buttery cake topped with tightly packed, burnished, sweet apples.
We started our testing with choosing the type of apple. Most apples turned mushy and watery and were simply too sweet, but crisp, tart Granny Smiths made the cut. Following the lead of recipes found in our research, we shingled the apples in the pan and poured the cake batter over the top. But once baked and inverted, our apple layer was shrunken and dry. The solution turned out to be increasing the number of apples, for a hefty layer of fruit. This effort yielded better results, but we found the apples to be overcooked, so we turned to a method uncovered in our recipe for Deep-Dish Apple Pie—we precooked half the apples by sautéing them on the stovetop then we cut the remainder thin, so they baked through evenly. For the butter cake, we tested milk, buttermilk, yogurt, and sour cream. Sour cream won hands down—its subtle tang balanced the sweetness of the cake and complemented the caramelized apples. And another addition—cornmeal—gave the cake a hint of earthy flavor and a pleasantly coarse texture. Our final discovery came when we attempted to release the cake cleanly from the pan. Typical recipes instruct a 5 to 10-minute cooling period, but we found that a full 20 minutes was required to allow the apple filling to set. And turning the cake out onto a rack to finish cooling let the bottom of the cake breathe, preventing sogginess, which is typical of so many upside-down cakes.
You will need a 9-inch nonstick cake pan with sides that are at least 2 inches high for this cake. Alternatively, use a 10-inch ovenproof stainless steel skillet (don’t use cast iron) to both cook the apples and bake the cake, with the following modifications: Cook the apples in the skillet and set them aside while mixing the batter (it’s OK if the skillet is still warm when the batter is added) and increase the baking time by 7 to 9 minutes. If you don’t have either a 2-inch high cake pan or an ovenproof skillet, use an 8-inch square pan.