
Preheat oven to 350° Fahrenheit.
Add peaches to large bowl with lemon zest, vanilla extract, cinnamon, and brown sugar. Toss to coat, then transfer to baking dish and arrange peaches evenly.
In another bowl, use pastry cutter to mix together all-purpose flour, brown sugar, cold butter, cinnamon, and salt. Mixture should be well combined and crumbly. Gently fold oats into flour mixture.
Sprinkle oat topping onto peaches. Lightly press topping into fruit.
Bake peach crisp approximately 30-35 minutes, or until topping is lightly browned and crisp.
Remove from oven and let cool 5-10 minutes. Serve warm with a scoop of vanilla bean ice cream (optional).