Preheat the oven to 450 degrees F. Place 4 tablespoons butter and the sliced peaches into a 10-12 inch cast iron skillet. Place the skillet in the center of the oven for 5-8 minutes, until the butter is browned.In a blender, combine the eggs, milk, flour, vanilla, 1 teaspoon cinnamon, salt, and 2 tablespoons melted butter. Blend on high for 30 seconds to one minute or until the batter is smooth. Make sure no large clumps of flour remain. Remove the hot skillet from the oven and pour the batter into the skillet. Place the skillet in the center of the oven and bake for 20-25 minutes or until the pancake is fully puffed and browned on top. DO NOT open the oven during the first 15 minutes of cooking or you might deflate your pancake.In a small bowl, combine the remaining 1 teaspoon cinnamon and the sugar. Remove the Dutch Baby from the oven and sprinkle with cinnamon sugar.  If desired, serve topped with whipped cream and maple syrup. EAT.