-cut in 3 cm pieces Vanilla ice cream Preheat oven to 190ºC Grease 10x10 inch baking dish. Combine first 5 ingredients in large bowl and mix thoroughly. Spoon evenly into dish. Combine oats, brown sugar, flour and butter in another large bowl (or processor) and mix until crumbly. Sprinkle over rhubarbapple mixture. Bake until top is lightly browned, about 40 minutes. Serve warm with vanilla ice cream.