Preheat oven to 450ºF (230ºC).
Whisk eggs together in a medium-sized mixing bowl. In the order listed above, add milk, vanilla, sugar, lemon zest, salt and flour continuing to whisk after each item is added until the batter is smooth and there are no lumps. You can also use a high-speed or immersion blender for this.
Place a 10-inch cast iron skillet in the oven on the middle rack and heat for 5 minutes. Remove skillet from oven and add butter, swirling it around until melted and it covers the bottom. Add blueberries and let sit for 1 minute. Pour in batter, return skillet to oven and bake for 15 minutes until the pancake is fully puffed up and browned. *Do NOT open the oven or the Dutch baby won’t rise properly!
Remove from oven, sprinkle with confectioners’ sugar if using and top with butter, more berries and/or maple syrup as desired. Enjoy!