Heat the oven to 450°F. Place a large, seasoned cast iron skillet in the oven as it preheats.
Combine eggs and milk in a bowl and whisk until thoroughly combined and batter is light. Stir in flour mixture cinnamon and vanilla. Whisk until the batter is thoroughly moistened and slightly lumpy, (do not overmix).
Use an oven mitt to remove the skillet from the oven. Add butter. Tilt pan to coat the sides and bottom evenly.
Pour the batter into the skillet and bake in the oven until puffed and golden brown on the sides, about 20-25 minutes. Remove the pancake from the oven and serve immediately with fresh fruit, honey, maple syrup or powdered sugar.