Preheat oven to 375º F. Grease or spray your casserole dish with cooking oil. Place peaches in a large bowl and set aside.
In a small bowl, mix granulated sugar and corn starch. Add lemon juice and zest. Add to peaches and stir.
In a medium bowl, add topping ingredients. Using a pastry cutter or your fingers, smash the butter into crumb-sized pieces.
Add the peach filling to the casserole pan, then cover with topping. Bake at 375ºF for 40 minutes, or until bubbly and golden.
Let cool for at least 10 minutes. Top with whipped cream or ice cream, if desired before serving.
Notes
The lemon juice serves two purposes, to provide a little tartness to balance the sweetness and to keep the peaches from browning.
Recipe Variations:
You can add a touch of cinnamon or allspice to the filling for an extra layer of flavor.
Add a little vanilla extract, fresh orange zest, or lemon juice to the peach mixture.
For something different, try using brown sugar instead of white sugar in the topping. It adds a nice deep, caramel flavor.
Storing Instructions:
In the fridge, the crisps can be stored in the fridge for up to a week. If you want it to last longer, you can store it in an airtight container or wrap it tightly with foil.
In the freezer, It also freezes well, so if you have any leftovers that you don't plan on eating right away, just pop them into the freezer.
Be sure to let it cool completely before freezing.
To reheat, simply thaw in the fridge overnight and then warm in the oven or microwave until fully heated through.