Preheat your oven to 375 degrees and remove the skin from your peaches with a vegetable peeler.
Combine sliced peaches in a bowl with all the other items for the peach mixture listed in the ingredients. Mix well so the sugar can begin pulling the juices out of the peaches. Cool in the refrigerator for 10 minutes.
In a separate bowl, combine all your dry ingredients for the crumble. Mix thoroughly.
Add butter and using a pastry cutter or fork, smash it into the dough mixture. You will find mix becomes piece-y and gritty with chunks of butter.
Remove the peaches from the refrigerator and add them to a baking dish. Bake for 10 minutes.
After 10 minutes remove the peaches from the oven.
Mix the hot water in with your topping ingredients. The dough this makes will be thick and have consistency similar to drop biscuits.
Add dollops of the topping to the hot peaches. Cover the top with spoonfuls of it.
Add back to the oven and bake for 35-40 minutes or until the Oatmeal topping is a warm brown.
Remove from oven and serve immediately with a scoop of vanilla ice cream and an additional sprinkle of cinnamon.