Make oat flour. Process 1 cup of the oats in a coffee grinder, blender, or food processor fitted with the blade attachment until it resembles flour, about 3 minutes. Transfer to a large bowl.
Make the crisp topping. Add the remaining 1 cup oats, sugar, and salt and stir until combined. Drizzle the butter and vanilla over the oat mixture and stir to combine. Set aside or store in the freezer in a zip-top freezer bag.
Add crisp topping. Scatter the crisp topping evenly over the fruit mixture, leaving large clumps intact.
Bake the crisp. Bake until the fruit juices are bubbling around the edges of the baking dish and the topping is golden and firm to the touch, 30 to 35 minutes.