Preheat your oven to 350℉. Line a 9x13 inch pan with parchment paper. I used butter to lightly grease the parchment. You can also spray with oil.
In a large bowl, beat the eggs with the sugar for a few minutes. Add in the milk, oil and vanilla and incorporate. Sift in the flour, baking powder and cinnamon. Mix to combine until smooth.
Add the apple pieces to your prepared pan and spread out to an even and mostly flat layer. Pour the batter evenly over the apples and use a rubber spatular to spread out as best you can. Bake for 25-30 minutes. May need to broil for a minute or two to get some color on top. Allow to cool and then sprinkle with some powdered sugar to garnish.
Notes
*I would use Fuji or HoneyCrisp apples here - something sweet. You can peel the apples or leave the skin on. I left the skin on.