Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners.

Peel and finely chop the apples. Melt the butter and let it cool slightly.

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

In a large bowl, combine the melted butter, granulated sugar, eggs, vanilla extract, and Greek yogurt. Mix until smooth.

Gradually fold the dry ingredient mix into the wet mixture, mixing until just combined.

Gently stir in the chopped apples until evenly distributed.

Scoop the batter into the muffin tins, filling each about 3/4 full.

Mix brown sugar and ground cinnamon for the topping. Sprinkle on each muffin.

Bake for 18–22 minutes or until a toothpick comes out clean.

Let the muffins cool in the pan for 5 minutes before transferring to a wire rack.