Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish or line it with parchment paper.

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

In a large mixing bowl, cream together the softened unsalted butter and light brown sugar until light and fluffy.

Add one egg and pure vanilla extract to the creamed mixture, beating well until smooth.

Gradually add the dry mixture to the wet mixture, alternating with buttermilk, mixing just until incorporated.

Gently fold in the pure maple syrup into the batter.

Pour the batter into the prepared baking dish, spreading evenly.

Bake for 20 to 25 minutes until golden brown and a toothpick comes out clean.

Prepare the maple glaze by whisking together powdered sugar and maple syrup in a small bowl.

Allow baked bars to cool for 10 minutes, then drizzle with glaze.

Slice into squares or rectangles and serve.