01 -
Set a rack in the center of the oven and heat it to 450°F. Keep a 9- or 10-inch cast iron skillet on low heat on the stove while mixing the batter.
02 -
Melt two tablespoons of butter in a small pan, then pour it into a blender. Toss in the eggs, milk, regular flour, white sugar, vanilla, zest, and salt. Blend well to make it smooth. This step avoids clumps.
03 -
Drop the rest of the butter into the cast iron skillet and heat it on medium-high. Once melted, toss in the blueberries and give it a little jiggle to spread them around.
04 -
Pour the batter on top of the berries immediately, then pop the skillet into the oven. Bake for roughly 15 minutes until it puffs up and turns golden.
05 -
Take it out of the oven, sprinkle some powdered sugar if you'd like, slice it up, and serve fast with some maple syrup.