Preheat the oven to 375 degrees.
Put the eggs, milk, butter, flour, sugar, and vanilla into a blender. Blend until incorporated.
Melt 1 tbsp of butter in a large cast iron skillet over medium-high heat. Place the apple slices into the skillet. Pour the batter over the apple mixture.
Remove from the oven, dust with powdered sugar and serve with berries and maple syrup.
Place the skillet into the oven on the center rack and bake for 35 minutes until golden and center is firm.