Preheat oven to 375 degrees.
Place 12" oven-safe skillet in oven.
Whisk together flour, 4 tablespoons of sugar, baking powder, ground cinnamon, and orange zest in a medium bowl.
In a separate bowl, whisk together milk, eggs, and 3 tablespoons of melted butter.
Whisk milk mixture into flour mixture just until combined.
Removed skillet from the oven and add the remaining tablespoon of butter, swirling the skillet to coat the pan.
Pour in the batter and smooth.
Sprinkle blueberries evenly.
Sprinkle remaining teaspoon of sugar over the top.
Bake for about 25 minutes or until cooked through.
Let cool for at least 5 minutes before serving. Dust with powdered sugar and serve with maple syrup if desired.