Pre heat oven to 375 degrees. Grease a pie dish or 8X8 inch casserole dish with cooking spray.
Combine the dry ingredients in a large bowl. Whisk together the wet ingredients in another bowl.
Layer the peaches on the bottom of the pie dish. Combine the wet and dry ingredients. Pour over the peaches.
Bake for 50-55 minutes until the top is golden brown and the oatmeal is mostly set. It will continue to firm up as it cools.