Food & Cooking Recipes Dessert & Treats Recipes Cake Recipes Plum Blueberry Upside-Down Cake 4.1 (21) 2 Reviews By Martha Stewart Test Kitchen Martha Stewart Test Kitchen The recipes developed by our test kitchen team have undergone a rigorous process of development and testing, ensuring that every element is optimal, from ingredient amounts to method and cooking time. This process includes triple-testing recipes to ensure they meet our high standards. The many stellar cooks and food editors who have been part of our team include Sarah Carey, Lucinda Scala Quinn, Jennifer Aaronson, Shira Bocar, Anna Kovel, Greg Lofts, Riley Wofford, Lauren Tyrell, and Lindsay Leopold. Editorial Guidelines Updated on January 16, 2019 Print Rate It Share Share Tweet Pin Email Prep Time: 15 mins Total Time: 1 hrs 5 mins Servings: 8 This moist and delicious cake turns out of the pan with a sweet, jamlike layer of fruit on top. Ingredients 10 tablespoons (1 ¼ sticks) unsalted butter, room temperature, plus more for pan 1 cup packed light-brown sugar 1 large firm but ripe black plum, cut into ½-inch wedges 1 ½ cups blueberries (7 ounces) 1 large egg 1 large egg white 1 tablespoon finely grated orange zest 1 ½ cups all-purpose flour (spooned and leveled) 1 teaspoon poppy seeds ¾ teaspoon baking powder ¼ teaspoon baking soda ½ teaspoon fine salt ½ cup buttermilk 1 teaspoon pure vanilla extract Directions Preheat oven to 375 degrees. Lightly butter an 8-inch round cake pan (2 inches deep); line bottom with parchment paper. Melt 2 tablespoons butter and pour into pan; swirl to coat paper. Sprinkle 1/2 cup brown sugar evenly over butter. Arrange plum evenly in pan, then add blueberries, filling in any gaps. In a large bowl, using an electric mixer, beat 8 tablespoons butter and 1/2 cup brown sugar on high until light and fluffy, about 3 minutes. Beat in egg, egg white, and orange zest until combined. In a medium bowl, whisk together flour, poppy seeds, baking powder, baking soda, and salt. With mixer on low, beat flour mixture into butter mixture until combined. Beat in buttermilk and vanilla until smooth. Transfer batter to pan. Tap pan firmly on counter several times to remove air bubbles; smooth top. Bake until cake is deep golden brown, juices are bubbling around edge, and a toothpick inserted in center comes out clean, about 45 minutes, rotating pan halfway through. Let cake cool in pan on a wire rack, 1 hour. Run a knife around edge of pan and invert cake onto a serving plate. Serve warm or at room temperature. (Store, covered, at room temperature, up to 2 days.) John Kernick Cook's Notes Make sure the fruit is packed snugly in the pan; it will shrink and lose volume as it bakes. Rate it Print