Step 1 Heat the oven to 425 degrees. Melt the butter in a large cast iron skillet.
Step 2 In a medium bowl, whisk together the eggs, flour, milk and sugar. Pour the batter into the hot skillet and place the skillet in the oven. Bake until puffed and golden brown, 20 to 25 minutes.
Step 3Remove from the oven and serve immediately.