01 -
Arrange an oven rack in the upper third and set oven to 190°C. Place a 25-centimetre cast iron skillet or oven-safe nonstick pan inside to preheat.
02 -
In a large bowl, whisk together flour, granulated sugar, baking powder, baking soda, and kosher salt until evenly mixed.
03 -
Microwave 2 tablespoons of unsalted butter in a small microwave-safe bowl, heating in 10-second bursts until melted, about 30–40 seconds.
04 -
Add buttermilk to the melted butter. Separate eggs, placing whites in a measuring cup and yolks in the butter mixture. Whisk until well combined.
05 -
Pour the buttermilk mixture into the dry ingredients. Stir gently with a spatula until most flour is moistened. Fold in egg whites just until incorporated; do not overmix.
06 -
Let the batter stand at room temperature for 10 minutes.
07 -
Carefully remove preheated skillet from oven. Add remaining 2 tablespoons butter, cut into 4 pieces, swirling to coat bottom and sides as it melts.
08 -
Transfer batter to skillet and spread into an even layer. Sprinkle blueberries evenly over the top.
09 -
Bake until pancake is puffed and golden brown, 25–30 minutes.
10 -
Slice into wedges and serve warm with maple syrup and additional blueberries if desired.