Preheat the oven to 425 degrees F (220 degrees C).
Combine eggs, milk, sugar, and vanilla extract in a bowl; whisk to combine. Combine flour, salt, and cinnamon in a second bowl. Whisk flour mixture into the egg mixture until batter is smooth.
Melt butter in an 8-inch cast iron skillet over medium-high heat. Pour in the batter and sprinkle blueberries on top.
Bake Dutch baby in the preheated oven until puffed and golden, 20 to 25 minutes. Remove from the oven, dust with confectioners' sugar, and serve immediately.
