Place the 10" (25-cm) Cast Iron Skillet into the oven and preheat to 425°F (220°C).
Whisk the eggs, milk, sugar, vanilla, and salt together in a medium bowl. Then, whisk in the flour.
When the oven is preheated, carefully remove the skillet from the oven and add the butter, swirling it to melt.
Pour the batter into the skillet and return it to the oven. Bake for 20 minutes. Reduce the oven temperature to 350°F (180°C) and bake for 5 more minutes.
Meanwhile, slice the strawberries with the Quick Slice. Add the heavy cream, powdered sugar, and the vanilla to the Whipped Cream Maker; replace and lock the lid. Pump the handle to make whipped cream. Remove the skillet from the oven. Serve the Dutch baby with the strawberries, blueberries, whipped cream, and powdered sugar.