Heat oven to 450 degrees. Line a 12-cup muffin tin with paper liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon and salt.

In a large bowl, using an electric mixer on medium speed, beat the brown sugar, granulated sugar and butter until fluffy, about 3 minutes. Add the eggs, one at a time, and beat until combined. Beat in the yogurt and vanilla extract.

Using a rubber spatula, fold in the dry ingredients and about 1 ¼ cups of the diced apple by gently scooping up some of the mixture from the bottom and folding it over them. Rotate the bowl and repeat until just combined. Do not overmix.

Divide the batter evenly among the liners, about a heaping ¼ cup each. Top with the remaining diced apple. Adjust the oven temperature to 350 degrees.

Bake until a toothpick inserted into the center of a muffin comes out with moist crumbs attached, about 25 minutes. Let cool slightly in the pan, then transfer the muffins to a rack to cool completely.

Meanwhile, prepare the topping: Combine the sugar and cinnamon in a small bowl. Brush the warm muffins with melted butter and dip into the sugar mixture. Serve warm or at room temperature.

Store leftovers in an airtight container at room temperature for up to three days or store in an airtight container in the freezer for up to one month. To reheat, wrap frozen muffins in foil and bake at 350 degrees until warm, about 10 minutes.