To crush the ice, put cubes in a clean towel and bash with a kitchen mallet or rolling pin.
To shave the ice, put cubes in a blender and pulse until desired size.
For the lime twist, remove the flesh and pith from some lime peel and cut a thin strip (twist this into the final drink). Alternatively, either a canelle knife with a parer or a zester with a twist cutter can be used.
Place amaretto, ice and lime juice in shaker and shake.
Pour contents into glass and garnish with lime twist.