01 -  Preheat oven to 350°F. Line a standard 12-cup muffin tin with paper liners or grease thoroughly. 
 02 -  In a large bowl, whisk together all-purpose flour, baking powder, baking soda, fine sea salt, ground cinnamon, and packed light brown sugar until evenly combined. 
 03 -  In a separate bowl, whisk eggs, whole milk, pure maple syrup, melted unsalted butter, bourbon, and vanilla extract until homogeneous. 
 04 -  Pour wet mixture into dry ingredients. Stir gently with a whisk or spatula until just combined, avoiding overmixing for optimal texture. 
 05 -  Fold in 3/4 cup of crushed mini pretzels and chocolate chips if using, distributing evenly throughout the batter. 
 06 -  Divide the batter equally among the prepared muffin cups, filling each approximately three-quarters full. 
 07 -  Sprinkle the remaining 1/4 cup crushed pretzels over the tops of the filled muffin cups. 
 08 -  Bake for 16 to 18 minutes, or until a toothpick inserted into one muffin emerges clean. 
 09 -  Allow muffins to cool in the pan for 5 minutes to set structure, then transfer each to a wire rack to cool completely. 
 10 -  Whisk powdered sugar, pure maple syrup, 1 teaspoon milk, and a pinch of salt in a bowl until smooth. Adjust with extra milk, a few drops at a time, for a drizzle consistency. 
 11 -  Drizzle glaze evenly over cooled muffins and let set before serving.