Pre-heat oven to 350 degrees F. Line a square, 8x8 baking pan with parchment paper.
In a medium bowl, combine oats, oat flour, baking powder, salt, and cinnamon with a spoon.
To the bowl of dry ingredients, add applesauce, peanut butter, maple syrup and diced peaches. Keep a handful of diced peaches to the side to add on top. Stir till just combined with a spoon or whisk.
Using a spatula, scrape the combined dry and wet ingredients out of the bowl into the prepared pan. It is a thick batter - that's good! Spread it out evenly in the baking dish. Top with a few diced peaches.
Bake in the pre-heated oven for 40 - 45 minutes or until an inserted toothpick comes out fairly clean.
Remove from the oven and let cool for about 5 - 10 minutes.
Serve warm with sliced peaches on top and Greek yogurt if you want.