Position a rack in the center of the oven and heat the oven to 350°F. Lightly butter a 9x2-inch round cake pan. Line the bottom with a parchment circle cut to fit the pan, lightly flour the sides, and tap out the excess.
In a medium bowl, whisk the flour, baking powder, baking soda, and salt until well blended. In a stand mixer fitted with the paddle attachment (or with a hand mixer), beat the butter and sugar on medium-high until well blended and fluffy, about 3 minutes. Add the eggs, one at a time, beating on medium speed until just blended, and adding the orange zest and vanilla with the second egg. Using a wide rubber spatula, fold in half the dry ingredients, then the yogurt, and then the remaining dry ingredients. Scrape the batter into the prepared pan and spread evenly. Bake for 15 minutes.
Meanwhile, make the topping.
Combine the peach slices, raspberries, sugar, and flour in a small bowl. Using a table fork, mix the ingredients to evenly coat the fruit and lightly crush the raspberries. After the cake has baked for 15 minutes, slide the oven rack out and scatter the fruit evenly over the top of the cake, working quickly. Continue baking until a toothpick inserted in the center of the cake comes out clean, another 25 to 30 minutes.
Let the cake cool on a rack for 15 minutes. Run a knife around the inside edge of the pan to loosen the cake. Using a dry dishtowel to protect your hands, lay a rack on top of the cake pan and, holding onto both rack and pan, invert the cake. Lift the pan from the cake. Peel away the parchment. Set a flat plate on the bottom of the cake and flip the cake one more time so that the fruit is on top. Serve warm or at room temperature.
nutrition information (per serving):
based on ten servings;
Photo: Scott Phillips