Do you ever argue with Martha Stewart? Well, I did last Thursday. But she started it! Who has a 6-inch cake pan in their kitchen, let alone FIVE 6-inch cake pans? I have a very well-(over)stocked kitchen, yet nary a 6-inch cake pan can be found. So I was like, "Whatever Martha," and decided to cut the recipe in half and bake it in a 9-inch cake pan (of which I have three). Martha could not be reached for comment, but the cake turned out beautifully. I always loved pineapple upside-down cake growing up because the top of the cake had crispy edges and each slice of pineapple was caramelized into sticky goodness. So it should not be a shock that should you, say, acquire nine pounds of plums on Tuesday, if you give them the same upside-down-cake-treatment, they'll turn into pretty darn tasty plums. And also cake.
Don't skip the cake flour here, because it really helps keep the cake texture light and moist (which is a word I hate except for when one is discussing cake). Also, the cake is best piping hot on the day it is baked, preferably a la mode (pictured here with Honey-Lavender ice cream from my work).
For the topping:
1/2 cup (1/2 stick or 4 oz) unsalted butter, room temperature
1 1/2 Tbsp maple syrup
1 teaspoon dark rum
1 cup light-brown sugar, packed
1/2 teaspoon vanilla extract
1/2 teaspoon coarse salt
2 lbs Damson plums (9-10)
For the cake:
3/4 cup all-purpose flour
3/4 cup cake flour
1/2 tablespoon baking powder
1/2 teaspoon salt
1/2 cup (1 stick) unsalted butter, room temperature, plus more for pans
1/2 cup granulated sugar
2 large eggs
1 teaspoon pure vanilla extract
1/2 cup + 2 Tbsp milk
1. Preheat the oven to 350 degrees. Spray a 9-inch round cake pan or a 12-cup muffin tin with non-stick spray. Line the bottom of the cake pan with a round of parchment paper, then spray again.
2. Make the fruit topping: Cream all of the topping ingredients together with a hand mixer for several minutes, until they are uniformly incorporated. (I used the hand mixer for the topping since I was already using my stand mixer for the cake.)
3. Spread the fruit topping evenly on the bottom of the cake pan with an offset spatula, or divide evenly between the muffin tins.
4. Slice the plums in half, wiggle out the pit, then slice each half into 1/4-inch wedges. Starting from the outside and working your way in, arrange the plums in the bottom of the cake pan in a circular pattern , using about 3-4 slices per muffin tin if you go that route.
5. For the cake: Sift together both flours, the baking powder and salt into a medium-sized mixing bowl Set aside. In the bowl of your stand mixer, beat the butter and granulated sugar until light and fluffy, 3 to 4 minutes, with the paddle attachment. Then mix in the two eggs and the vanilla.
6. On low speed, mix in the dry ingredients and the milk by adding them incrementally; alternate by mixing in 1/3 of the flour first, then some of the milk. Repeat until flour and milk are both incorporated, but turn off the mixer in between additions so you won't accidentally over-mix the batter and end up with a tough cake.
7. Scrape the batter into the greased cake pan and spread evenly over the plums. Or for the baby cakes, divide the batter evenly between the muffin tins, about 2 oz of batter per tin. Bake until the cake is golden brown (and delicious), 45-50 minutes, or 25-30 minutes for the baby cakes. Allow the cake to cool in the pan for 30 minutes, or 20 minutes for the baby cakes. Using a small offset spatula or paring knife, loosen the cake from the sides of the pan, then carefully turn it upside down and let the cake slide out of the pan (placing your serving plate directly over the cake pan before you invert it will help). Peel off the parchment, 'cause you don't wanna eat that or whatever. Slice into wedges and serve immediately! Or, if you made the baby cakes, stand around the pan with your boyfriend and pry the cakes from the pan with your fingers when they're still too hot, then blow on each bite to cool it because you don't want to wait any longer Repeat as necessary, or until you decide you've probably hit your butter quota for the day.