Preheat oven to 425°. Melt butter in a 12-in. ovenproof frying pan over high heat. Add brown sugar and cinnamon, swirling to combine. Add apple and cook until just starting to soften, about 3 minutes.
Meanwhile, in a blender, whirl together eggs, salt, flour, and milk. Pour egg mixture into pan and bake until puffed and brown, about 15 minutes. Sprinkle with lemon juice and powdered sugar.
Note: Nutritional analysis is per serving.