To make this Dutch Baby, start by adding all of your batter ingredients to a blender.
Blend your ingredients together on low, for about 20 seconds, until just combined.
Then, allow the batter to "rest" in the blender for about 10 minutes.
While the batter is "resting," preheat your oven to 450 F and grease a 10 inch cast iron skillet with melted butter.
Then, wash your blueberries and add them to the greased cast iron skillet, tossing them to coat them in the butter.
Next, pour the batter on top of the blueberries, making sure that it is evenly dispersed across the skillet.
Finally, transfer the skillet to the oven and bake for 17-18 minutes, until the Dutch Baby is fluffy and lightly browned on top.
Once it's done, remove it from the oven, dust it with powdered sugar and maple syrup (if desired), serve, and enjoy!