Preheat your oven to 350°F (175°C) and prepare a 9x13-inch baking pan.
In a large mixing bowl, whisk together the dry ingredients: flour, sugar, baking powder, salt, and cinnamon.
In another bowl, mix the wet ingredients: milk, melted butter, eggs, and vanilla extract. Stir until blended.
Pour the wet mixture into the dry ingredients and stir gently until just combined.
Spread the batter evenly into the prepared baking pan and smooth the top.
Bake for 20-25 minutes, checking for doneness with a toothpick.
Allow the bars to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Prepare the glaze by whisking together powdered sugar, maple syrup, and milk until smooth.
Drizzle the glaze over the cooled bars and let it set before slicing.