Pre-heat your oven to 350 degrees F.
Grease a 9x13 inch casserole dish.
In a large bowl, toss peaches with cinnamon, vanilla, 3 tablespoons sugar and 3 tablespoons flour. Pour the peaches into the greased casserole dish.
In a separate large bowl, combine 1 cup flour with old fashioned oats, and brown sugar. Cut in butter until you have a crumbly consistency.
Pour the crumbly topping on top of the peaches.
Bake in the oven, uncovered for 45-50 minutes.
*Notes: Some of you have suggested that this calls for too much butter. If a cup seems like too much for you, feel free to reduce the amount to 1/2 cup. If you want your Fresh Peach Crisp to be extra crisp, bake for 5-10 minutes longer, making sure to keep a close eye on it. I personally love the end result using a full cup of butter.