Heat the oven to 425°F (220°C). Place the unsalted butter in a 9 x 13-inch baking dish and set the dish in the oven as it preheats, allowing the butter to melt without letting it brown excessively.

Blend or whisk the eggs, whole milk, flour, vanilla extract, and salt until the batter is smooth and lump-free. If using a blender, mix only until combined so the pancake stays tender.

Carefully remove the hot baking dish from the oven. Swirl the melted butter across the bottom, taking care because both the dish and butter will be very hot.

Pour the batter into the hot, buttered dish. The batter should begin cooking at the edges right away, which helps create the signature puffed border.

Bake for approximately 20–25 minutes, without opening the oven door, until the pancake is puffed, deeply golden at the edges, and set in the center.

Remove the pancake from the oven and serve immediately with powdered sugar, fresh fruit, lemon juice, or maple syrup. Expect it to deflate somewhat as it cools; this natural settling is part of its texture.