Plum Upside Down Cake

Ingredients

• 1 1/4 stick butter, softened
• 1/4 cup plus 2 tablespoons brown sugar, firmly packed
• 4 plums, pitted and sliced
• 5 tablespoons buttermilk OR 4 tablespoons milk plus 2 teaspoons milk and 1 teaspoon lemon juice
• 3/4 cup cake flour
• 1/2 teaspoon baking powder
• 1/8 teaspoon baking soda
• 1/4 teaspoon cinnamon
• Pinch salt
• 1/2 cup granulated sugar
• Zest of 1/2 an orange
• 1 egg
• 1 teaspoon vanilla extract

Directions

1. Heat the oven to 350 degrees F. Coat the inside of each ramekin with butter. In a medium saucepan over medium heat, melt 3/4 stick (6 Tbsp) of the butter, then whisk in the brown sugar until the mixture is smooth. Spoon the sauce into the prepared ramekins, sharing it evenly.
2. Set the plum slices in a single layer in the bottom of each ramekin.
3. In another bowl, whisk the cake flour, baking powder, baking soda, cinnamon and salt together with some energy, so the batter bakes evenly.
4. With an electric mixer, beat the granulated sugar and orange zest with the remaining butter, 1/2 stick (1/4 cup or 4 Tbsp), until combined. Mix in the eggs and vanilla. Add the flour mixture and the buttermilk, or lemon-soured milk, in alternating additions, mixing them into the batter.
5. Portion the batter into the ramekins. Set the ramekins on a rimmed baking sheet, then slide the sheet onto the middle rack. Bake at 350 degrees F for 35 to 40 minutes, turning the baking sheet halfway through so the cakes cook evenly. They’re ready when the tops feel set and a toothpick or skewer poked into the center comes out without raw batter, though plum juice may make it damp.
6. Take the cakes out of the oven and cool them on a rack until they are no longer hot when touched. Loosen the sides with a paring knife, turn each ramekin over onto a plate, and carefully lift it away.
7. Serve plain, or add whipped cream or vanilla ice cream.