Preheat the oven to 350°F (175°C). Lightly grease your baking dish.
Make the peach filling: In a large bowl, combine peaches, cornstarch, cane sugar, lemon juice, and vanilla extract. Stir gently to coat.
Transfer to dish: Pour the peach mixture into your baking dish, spreading it evenly.
Make the crumble: In a small bowl, mix oats, almond flour, brown sugar, walnuts, cinnamon, and sea salt. Add cubed coconut oil or butter and use your fingers or a fork to work it into a crumbly mixture.
Top the peaches: Sprinkle the crumble evenly over the peaches.
Bake: Place in the oven and bake for 35 minutes, until the topping is golden and the peach juices bubble up around the edges.