Preheat the oven to 350°F. Grease a 9" round cake pan. To make the topping, pour melted butter into pan and sprinkle brown sugar on top, swirling to cover the entire bottom of the pan. Place a single layer of peach slices and blackberries onto the melted butter and sugar mixture and set aside.
¼ cup (56g) unsalted butter, ⅓ cup (66g) brown sugar, 15 ounces canned peaches*, 1 handful blackberries*
In a small bowl, whisk the flour, baking powder, salt, and baking soda together. Set aside.
1 ½ cups (222g) flour*, 2 teaspoons baking powder, ½ teaspoon salt, ¼ teaspoon baking soda
Using a hand mixer or a stand mixer fitted with the paddle attachment, cream the butter with the sugar. Add the Greek yogurt, milk, and vanilla extract and mix until combined. Add the dry ingredients into the wet ingredients and stir on low speed until just combined.
½ cup (113g) unsalted butter, ⅔ cup (133g) granulated sugar, ½ cup (113g) Greek yogurt, ½ cup (120ml) milk, 1 teaspoon vanilla extract
Transfer the batter into the prepared pan, spreading evenly. Place the cake pan onto a baking sheet (optional, but recommended). Bake for 35-40 minutes or until a toothpick inserted into the center of the cake comes out clean.
Allow the cake to cool in the pan for 10 minutes. Use a knife to separate the sides of the cake from the pan, then invert cake onto a plate.
Notes
You can use fresh or frozen peaches instead of canned peaches for this recipe, and fresh or frozen blackberries.
You can use either AP flour or a gluten free flour blend, depending on whether you are looking to make this cake gluten free or not.