Preheat your oven to 350°F (175°C).
Grease a 9x13 inch baking pan or line it with parchment paper.
In a medium bowl, combine melted butter, brown sugar, and granulated sugar. Mix until well blended.
Add the eggs and vanilla extract, and whisk until the mixture is smooth.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry mixture to the wet ingredients, stirring until just combined.
Fold in the chopped apples gently.
Pour the batter into the prepared pan and spread it evenly.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Let the blondies cool in the pan for about 10 minutes before transferring them to a wire rack.
While the blondies cool, prepare the maple glaze by whisking together powdered sugar and maple syrup until smooth.
Once the blondies are completely cool, drizzle the maple glaze over the top.
Slice into squares and serve.