Brush a 10″ cast iron skillet (or 9×7 baking dish) with oil and set aside.
In a large bowl, toss peaches with 1/4 cup of the brown sugar and the cornstarch.
In a separate bowl mix oats, almond flour, salt, spices and remaining two tablespoons of brown sugar. Stir. Add tahini, then use a fork (or your hands!) to work it into the dry mixture until moist and crumbly.
Transfer peaches to the skillet or baking dish and top with the crumbly oat mixture.
Bake 30 minutes or until topping is browned and peaches are bubbling and tender.