01 - Preheat the oven to 350°F. Grease and flour a 9-inch round cake pan.
02 - In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt.
03 - In a large bowl, cream the softened butter and sugar until light and fluffy. Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
04 - Mix in half of the dry ingredients, then add the plain yogurt. Gently fold in the remaining dry ingredients until just combined.
05 - Gently fold in the diced pears and mixed berries, ensuring even distribution without overmixing.
06 - Pour the batter into the prepared pan and spread evenly with a spatula.
07 - Bake for 40 minutes, or until a toothpick inserted into the center comes out clean.
08 - Cool the cake in the pan for 10 minutes before transferring it to a wire rack to cool completely. Optionally dust with powdered sugar before serving.