Preheat oven to 350° and prepare a medium sized baking dish (8X8 square pan, pie pan, round cake pan, casserole dish, etc.) by greasing with butter.
Peel and thinly slice 6-7 large peaches (8-10 if smaller in size).
In a bowl toss together sliced peaches, flour, sugar, salt and vanilla to combine. Gently add in raspberries and toss a few times. Dump into prepared baking dish.
In a bowl whisk together brown sugar, flour, oats, cinnamon and salt. Cut cold butter into cubes and cut into the dry ingredients using two forks, your fingers, or a pastry cutter. Once properly mixed there will still be pea sized chunks of butter and the ingredients will be throughly combined and stick together when pressed between two fingers. Work quickly as to not melt the cold butter.
Using your fingers, crumble the topping over the fruit in prepared baking dish. Bake in middle rack of preheated oven for 40-50 minutes until topping is crisp and golden brown and fruit filling is bubbling.