Place an 8-inch (20-cm) cast-iron skillet in the oven and preheat the oven to 425°F (220°C).
In a blender, pulse the eggs until frothy. Add the gluten-free flour, milk, and vanilla. Blend until smooth. Let the mixture rest for 15 minutes while the oven preheats.
Once the oven is heated, use oven mitts to remove the skillet. Add the butter to the skillet then carefully swirl the melting butter to coat the pan’s edges. Be careful, as the pan will be smoking hot!
Immediately pour the batter into the buttered pan. Place the skillet back in the oven and bake for 20 minutes. Do not open the oven during this time or the Dutch baby will not rise properly.
Use oven mitts to remove the skillet from the oven and top it with sliced strawberries. Serve hot with maple syrup and a sprinkle of powdered sugar (optional).