First, blanch the artichokes by boiling them for a few minutes and then plunging them into ice water (see more details and instructions at the link)

Use tongs to remove from the water and place on the towel.

Drain them well and pat them dry

Place the blanched and dried artichokes in a single layer on a baking sheet and pop them in the freezer

Once they're frozen solid, transfer them to airtight freezer-safe containers or baggies