Preheat the oven to 425°F (220°C). Place a 10-inch cast iron skillet in the oven while it heats to get hot.
In a blender, combine 3 large eggs, 3/4 cup milk, 3/4 cup all-purpose flour, 2 tablespoons granulated sugar, 1 teaspoon vanilla extract, and a pinch of salt.
Blend the mixture for 10 seconds, scrape down the sides of the blender, then blend again until the batter is completely smooth.
Let the batter rest at room temperature for at least 15 minutes.
When the batter has rested and the oven is preheated, carefully remove the hot skillet from the oven using oven mitts and set it on a heatproof surface or trivet.
Add 3 tablespoons butter to the hot skillet. Allow the butter to melt fully and swirl the skillet so the butter coats the bottom and sides.
Quickly pour the rested batter into the hot, buttered skillet and immediately return the skillet to the oven.
Bake for 15–20 minutes, until the Dutch baby is puffed and golden brown at the edges.
Remove the skillet from the oven, transfer the Dutch baby to a serving plate or serve from the skillet, and dust with powdered sugar.
Top with fresh berries, whipped cream, and drizzle honey or syrup as desired. Cut into slices and enjoy.