2. Mix oats, flour, sugar, and baking powder in large bowl. Cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs.
3. Press 3 cups oat mix firmly onto bottom of 9 inch square baking pan. Spread jam over crust. Mix nuts with remaining crumb mixture; sprinkle over jam.
4. Bake 30 mins or until topping is lightly browned. Cool completely on a wire rack.