If you have multiple inputs relating to the same value, you can use bind:group along with the value attribute. Radio inputs in the same group are mutually exclusive; checkbox inputs in the same group form an array of selected values.
In this case, we could make the code simpler by moving the checkbox inputs into an each block. First, add a menu variable to the <script> block...
let menu = ['Cookies and cream','Mint choc chip','Raspberry ripple'];
...then replace the second section:
<h2>Flavours</h2>{#each menu as flavour} <label> <inputtype="checkbox"bind:group={flavours} name="flavours"value={flavour} /> {flavour} </label>{/each}
It's now easy to expand our ice cream menu in new and exciting directions.