A shakerato is basically an espresso and sugar or simple syrup shaken over ice. Shaking a shot (or two!) of esspresso in a cocktail shaker along with some ice is a quick an easy way to cool down a freshly brewed espresso.
Shaking the espresso with ice helps cool it down. But it also creates a wonderful texture. The bold espresso flavor is mellowed just a bit. And the shaking adds some air which makes the espresso’s crema frothy and full of flavor.