01 - Preheat oven to 350°F. Grease and line a standard 9x5-inch loaf pan with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon until evenly blended.
03 - In a large bowl, whisk eggs, buttermilk, maple syrup, sugar, melted butter, bourbon (if using), and vanilla extract until smooth.
04 - Gradually add dry ingredients to the wet mixture, mixing gently until just combined. Avoid overmixing to prevent a dense loaf.
05 - Pour the batter into the prepared pan and smooth the top. In a small bowl, mix sugar and cinnamon for topping and sprinkle evenly over batter.
06 - Bake the loaf for 48 to 55 minutes, or until a toothpick inserted in the center comes out clean.
07 - Allow loaf to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.