Blend all ingredients except butter and maple syrup until smooth.
In a 10” cast iron skillet, melt butter until browned and swirl around pan, including sides.
Just before adding batter, drizzle maple syrup into the brown butter.
Pour batter into hot skillet and immediately transfer to oven.
Bake for 20 - 25 minutes until golden brown and risen. Serve with powdered sugar and maple syrup.
Notes
Make sure your cast iron skillet is really well seasoned and used. It should be virtually non-stick, otherwise the brown butter and maple syrup mixture may stick or burn.
To clean the pan after, heat the pan back up for 5 minutes on the stove and then clean with hot water. It’ll help release any residual residue.
If your blender cup is too small to fit all the ingredients, take a chopstick and push the ingredients down, mixing to make room.
Serve immediately when it comes out of the oven so it doesn’t deflate. Although I’ve eaten if for leftovers the next day and toasted it - the sugar caramelizes and gets crunchier, which I would highly recommend.