In a medium bowl, combine all ingredients for the cranberry layer.
Spread evenly into the pan over the base.
Spread the 1/3 crumble topping evenly over the cranberry layer. Can use your hand to squeeze crumble topping to form larger crumbs if preferred.
Place mandarin orange slices on top in the design you like.
Bake at 360 F for 50-60 minutes until the cranberries are starting to bubble in the centre of the pan.
Cool completely and refrigerate before cutting into bars. Refrigerate bars and store up to 4 days. Wrap and freeze bars to keep them longer.