Best app for a pick n mix sweet selector that allows quantity as well as multiple selection

[SweetArture]

Hello, I am the owner Sweet Arture of a pick and mix ( pick n mix ) online business https://www.sweetarture.com/products/pick-n-mix and we have an app for doing pick and mix, but i want to be able to add quantity of each product so you can select the amount of each sweet. anyone know an app?