PREHEAT oven to 375° F.
FOR APPLE LAYER:
ARRANGE apples in 13 x 9-inch baking pan. Combine morsels, sugar, flour and cinnamon in small bowl; sprinkle over apples.
BAKE for 20 minutes.
COMBINE flour and sugar in medium bowl. Cut in butter with pastry blender or two knives until crumbly. Stir in nuts and oats; sprinkle over apple layer.
BAKE for an additional 30 to 40 minutes or until apples are tender and topping is lightly browned. Cool slightly. Serve warm with ice cream, if desired.