Preheat oven to 425 degrees. Place 4 individual sized cast iron pans in oven to preheat. (or one 10 inch cast iron skillet)
Place the flour, sugar, salt, milk, vanilla, eggs and zest into blender and process for 30 seconds. Let rest for 1 hour at room temp or overnight in refrigerator. (If refrigerating, allow batter to come to room temp prior to baking)
Carefully remove hot pans from oven and place 1 tsp of butter into each. Swirl to melt.
Carefully pour the batter into the preheated skillet. Sprinkle with half of the fresh raspberries
Bake on the middle rack of the oven for 15-20 minutes or until the edges are puffed and brown.
Sprinkle with remaining fresh raspberries and dust with powdered sugar before serving.
Recipe by Sugar Plum Sisters at https://sugarplumsisters.com/2015/02/raspberry-dutch-babies/