Preheat oven to 375°F. Set aside a 9-inch deep dish pie pan.
In a large bowl, thoroughly whisk together jelly, arrowroot starch, and lemon juice. Add grapes and mix well. Pour the grape mixture into the reserved pie pan.
In another large bowl, mix coconut oil, peanut butter, milk, and vanilla extract until evenly incorporated. Add oats, flour, sugar, and salt and mix until well combined. Crumble the topping evenly over the grapes.
Bake until the filling is bubbling and the top is golden, about 35 - 40 minutes.
Let cool for at least 10 minutes before serving.
*If you don't keep a gluten-free diet, feel free to use conventional oats and wheat flour.