Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.
In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, salt, and cinnamon until well combined.
In another bowl, mix the melted butter, buttermilk, eggs, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Spread the batter evenly into the prepared baking pan.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bars to cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.
For the glaze, whisk together the maple syrup and powdered sugar in a small bowl until smooth.
Once the bars are completely cool, drizzle the maple glaze over the top and let it set for a few minutes before slicing.