Preheat oven to 375ºF. Lightly grease a 9×13 baking pan.
In a medium bowl, add spelt flour, oats, sugar, cinnamon, and salt. Stir to combine. Add butter; using your hands or a pastry cutter, incorporate into the dry ingredients until the mixture resembles coarse sand. Place 2/3 of the mixture into the pan; press down into an even layer.
In a medium bowl, add all ingredients for the peach filling. Stir to combine. Pour on top of the crust and spread into an even layer.
Evenly distribute the rest of the crust/topping mixture on top of the peaches.