• Preheat the oven to 350 degrees F. Line an 8x8-inch baking pan with parchment paper or grease generously with butter.
• In a large mixing bowl whisk the butter, both sugars, egg, salt, and cinnamon together until smooth
• Add the flour, oats, white chocolate chips and cranberries. Stir gently just until combined - the mixture will be thick.
• Spoon the batter into the pan and spread out evenly from edge to edge.
• Bake 25 minutes until lightly golden around the edges - a toothpick from the center should come out mostly clean with a few wet crumbs - not wet batter - attached.
• Cool completely.

Make the icing:

• Stir the confectioners' sugar, vanilla and heavy cream a little at a time until smooth and creamy. Add more heavy cream a little at a time until it reaches a soft spreading consistency.
• Smear over the bars from edge to edge.
• Remove the bars from the pan using the parchment to a cutting board and cut into 12 squares with a large chef's knife.
• Store tightly covered in a cool dry place up to 1 week.