Shake Shack Inc. /zigman2/quotes/209397077/composite SHAK +3.35% launched a limited-time Buffalo-spice menu that includes a Buffalo Chicken sandwich and Buffalo-spiced French fries with cheese, starting Tuesday for customers using the app. The menu will be available nationwide from Jan. 28 through April 25. The burger chain is also introducing two limited-time shakes: The Wake & Shake made with coffee, orange zest, maple syrup and vanilla custard; and the Chocolate Pie Shake with chocolate ganache and croissant cookie crumbles. Shake Shack said earlier this month that 2021 revenue is expected to beat Street expectations. Shake Shack stock has sunk 41.7% over the past year while the S&P 500 index /zigman2/quotes/210599714/realtime SPX +0.21% has gained 13.4%.