Preheat your oven to 180°C (350°F) and line a 12-cup muffin pan with paper liners.

In a large mixing bowl, whisk together melted butter, granulated sugar, brown sugar, Greek yogurt, milk, eggs, vanilla extract, cinnamon, and kosher salt until smooth.

In a separate bowl, sift together flour, baking soda, and baking powder. Gradually add to the wet ingredients, stirring until just combined.

Fold in the peeled and chopped apples evenly throughout the batter.

Fill each muffin liner almost to the top with batter.

In a small bowl, mix together flour, brown sugar, cinnamon, kosher salt, and melted butter for the streusel topping, until crumbly.

Sprinkle the streusel mixture generously over each muffin before baking.

Bake for 18–20 minutes, checking for doneness with a toothpick.

Once baked, cool in the pan for 15 minutes before transferring to a wire rack. Prepare the glaze and drizzle over the muffins.