Once they've cooled, layer them in an airtight container with parchment paper between each layer so they don't freeze together or make a mess while thawing.
Hold off freezing any decorated cookies, as the powder, frosting, or ganache won't keep as well as the bare cookies. The same rule applies when freezing dough.
To thaw, refrigerate them at room temperature or microwave them in 10-second intervals. Just ensure they're laid evenly on a flat, open surface to prevent sogginess.