Preheat your oven to 350°F (175°C). Prepare a 9x13 inch baking pan by lining it with parchment paper or greasing it.

In a large bowl, whisk together flour, baking soda, baking powder, salt, and nutmeg.

In another bowl, cream butter and sugar together until light and fluffy.

Mix in the egg, vanilla extract, and buttermilk with the creamed mixture until smooth.

Gently fold the dry ingredients into the wet mixture until just combined.

Pour the batter into the prepared pan and spread evenly.

Bake for 18-20 minutes or until a toothpick comes out clean.

Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

For the glaze, whisk together powdered sugar, maple syrup, maple extract, and milk until smooth.

Once the bars are cool, drizzle the glaze over the top and let set before slicing.

Slice into squares and serve warm or at room temperature.