Peel Peaches and slice into ¾ inch thick slices. Add the sliced peaches to a medium size bowl. Add ¼ cup sugar and toss to coat. Allow peaches to sit for about 20 minutes, to allow the sugar to pull some of the juice out of them.

To make crumble topping, add all topping ingredients to a bowl. Use a pastry blender or fork to cut in butter until mixture resembles small crumbs. Refrigerate.

Preheat oven to 375 degrees F.

Drain the peaches, reserving the peach juice, and placing the peaches in a large bowl.

Measure out ¼ cup of the peach juice and add it to a small bowl (you can discard the rest, or drink it because it's delicious!). Stir in the flour, lemon juice, vanilla, salt, and cinnamon. Pour mixture over peaches and toss to combine.

Pour peaches into a 8x8'' or similar size dish. Sprinkle oat topping evenly over the top. Bake for 30-35 minutes or until golden brown and top is set.

Remove from oven and cool for at least 10 minutes before serving. Serve with vanilla ice cream, if desired.