Melt half of the butter in the microwave for 30 seconds.
Add sugar and orange zest to a small mixing bowl and mix together until the sugar turn slight orange and fragrant.
In the same bowl, add flour and salt and mix together thoroughly with a whisk.
Transfer the flour mixture to a food processor, and add eggs, milk, vanilla and the melted butter.
Mix until everything is thoroughly combined, about 30 seconds.
Let the batter rest while you preheat the oven to 425°F along with the cast iron pan.
When the oven is ready, take out the pan and add the rest of the butter to it, swirl around to coat the bottom and the side completely.
When all the butter has melted, add the batter to the pan and put it back into the oven.
Bake for 20 minutes without opening the oven door to allow the dutch baby to completely puff up.
While the dutch baby is baking, add the heaving whipping cream, sugar and vanilla extract to a mixing bowl and beat on medium high speed until stiff peak.
Serve with fresh berries, whipped cream and powder sugar.