Use this recipe to make our Shortbread Rhubarb Sandwich Cookies.
Fill a large bowl with ice and water for an ice bath. Cook ingredients in a medium saucepan over low heat until rhubarb breaks down and begins to thicken, 10 to 12 minutes. Set pan in ice bath to stop the cooking. When cool, refrigerate until completely cold and set, about 2 hours or up to 1 week.