Spray bottom of Dutch oven; preheat oven to 325 degrees Fahrenheit.

Combine tart apples and raspberries in bowl; toss lightly with sugar. In another mixing bowl, combine flour, remaining sugar, and cinnamon.

Cut in the softened butter with a pastry blender until it resembles crumbs. Butter must be evenly distributed. Stir in oats and walnuts. Spoon fruit mixture into Dutch oven. Scatter the crumbled mixture over the fruit and cover evenly.

Bake covered for 60 to 70 minutes until fruit is soft and tender. Serve warm and top with a scoop of vanilla bean ice cream!