In a blender, combine the flour, eggs, milk, salt, and 2 tablespoons of the melted butter and blend until smooth with no lumps, 20 seconds.
In a 10-inch cast-iron skillet, heat the remaining 2 tablespoons melted butter over high heat until foamy. Add the batter and immediately put the skillet in the oven. Bake until the pancake is deep golden brown in color and puffed up on the edges, about 18 minutes.
Remove from the oven, add the mixed berries in the center of the pancake and dust with powdered sugar. Slice into pieces and pour honey over. Serve warm.