Preheat your oven to 425°F (220°C).
Place a cast-iron skillet or oven-safe pan in the oven to heat.
In a mixing bowl, whisk together eggs, milk, flour, salt, and sugar until smooth.
Carefully remove the hot skillet from the oven.
Add butter to the skillet and swirl to coat the bottom.
Pour the batter into the skillet over the melted butter.
Return the skillet to the oven immediately.
Bake for 15-20 minutes, or until the pancake is puffed and golden.
Remove from the oven and let it cool slightly.
Serve with your favorite toppings.