Step 1: Preheat your oven to 350°F (175°C). Grease and flour a round 9-inch cake pan.
Step 2: In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, ground cinnamon, and salt. Set aside.
Step 3: In a separate large bowl, combine the melted butter and granulated sugar. Mix well, then add the eggs one at a time, followed by the plain yogurt.
Step 4: Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined.
Step 5: Fold in the chopped and peeled apples until evenly distributed.
Step 6: Pour the batter into the prepared cake pan and bake for 35-40 minutes, or until a toothpick comes out clean.
Step 7: Let the cake cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely.
Notes
For added flavor, consider adding a teaspoon of vanilla extract. This cake can be served warm or at room temperature.