Place the top rack of your oven just above the center position and pre-heat oven to 425°F. Don't forget to remove any pots and pans you have hiding in your oven before your preheat!
Combine the flour, eggs, milk, cinnamon, vanilla, sugar, and salt in a medium bowl and stir until just combined. Pour the batter into a blender and blend until aerated (it will be bubbly) and no clumps remain, approximately 1 minute.
Use the butter to thoroughly grease the exposed surface of the skillet and then place in the hot oven just until melted. Remove the hot pan from the oven and carefully swirl the butter in the pan to ensure the butter is evenly distributed across the bottom of the skillet.
Pour the blended batter into the center of the hot skillet and place in the hot oven. Cook until the edges are puffed up and golden brown, approximately 20 minutes. Turn off your oven and allow the skillet to remain in the oven for 5 additional minutes.
Remove from oven and cool for a couple of minutes before slicing. Serve immediately topped with fresh fruit, powdered sugar, and/or maple syrup, if desired. Enjoy!