Preheat oven to 350°F and prepare a 9 by 5 inch loaf pan by coating it with melted butter then dusting with flour, tapping out excess In a large bowl whisk together all-purpose flour, packed light brown sugar, baking powder, baking soda, and salt until evenly combined In a medium bowl whisk the melted butter, lightly beaten egg, and whole milk until smooth and blended Pour the wet mixture into the dry ingredients and whisk gently until just combined, stop when you no longer see streaks of dry flour to avoid over mixing Fold cranberries into the batter gently so they are evenly distributed without crushing them Transfer the batter into the prepared loaf pan and smooth the top, sprinkle turbinado sugar over the surface if using for a crunchy top Bake on the middle rack for about 1 hour and 15 minutes or until a toothpick inserted into the center comes out clean, begin checking after 60 minutes as oven temperatures vary Remove the pan to a wire rack and allow the loaf to rest for 30 minutes, invert onto the rack then immediately turn right side up to cool completely before slicing Slice with a serrated knife after the loaf is fully cooled for clean even slices Serve plain, with softened butter, or a light spread such as cream cheese or honey if desired