 Shake Shack Inc. SHAK, 0.41 said Tuesday that it has partnered with Milk Bar to launch limited-time milkshakes. The Cornflake Chocolate Drizzle Shake, made with Milk Bar Cornflake Crunch and malted vanilla frozen yogurt, and Chocolate Birthday Cake Shake, made with Milk Bar BDay crumbs and frosting, will be available September 3 through November 1. 