In a large bowl, combine the oats, sugar, flour, cinnamon and salt. Add in the butter and use your hands to evenly distrubute it thorughout the oat mixture. I take at least 5 full minutes and mix with my hands, making sure all of the crumble is moistened and, well… crumbly. You want all of the flour mixed in and everything combined. Add in the vanilla extract and combine again with your hands. Sprinkle it evenly over top of the fruit. Bake for 30 to 35 minutes, or until the crumble on top is golden and crunchy.