Preheat oven to 425°F. Place butter in large 10-inch cast iron skillet. Transfer to oven and bake until melted, about 5 minutes
Meanwhile, place the Blending Stick attachment on blender base. Add flour, milk, eggs, vanilla and 1 tablespoon sugar in Beaker. Blend on high speed until smooth, about 1 minute. Pour batter into prepared skillet. Bake until golden-brown and puffed, about 20 to 25 minutes.
Meanwhile, place Whisk attachment on blender base. Add heavy cream and remaining sugar in clean Beaker. Whisk on high speed until stiff peaks form, about 1 minute. Set aside.
Place pistachios in Chopper attachment and cover with lid. Place blender base on Chopper attachment. Pulse on high speed until roughly chopped. Top Dutch baby with the whipped cream, chopped pistachios, powdered sugar and strawberries. Serve and enjoy.