Choosing different flavors

I’m building my webiste to sell cookies online.
I would like to give customers the choice between a box of 6,12 or 18 cookies. They will be able to choose the flavors they want.
Any idea how i can do that ? I want to do something similar as on the pic. They select “Box of 12 Cookies” and go to the second page to choose their flavors .
Thanks !!