Its actually a lot easier than it looks, its just a case of building up a pattern line by line. I used the same simple biscuit recipe I use for my Christmas biscuits. http://emilykatemakes.blogspot.co.uk/2013/12/christmas-hamper-ideas.html
To ice the biscuits, I used Whitworth royal icing sugar with water to make the icing. I realised if the icing is warm its easier to pour onto the biscuits and spread evenly. Wait until the base icing is completely set and hardened before icing on the lace design.
For the icing on the top, make sure its quite thick, so it won't spread out of the pattern when piped onto the biscuits. I used the disposable plastic icing bags you can buy from most big supermarkets, then you know there's no chance of icing escaping through any unknown holes, and you can choose how thick you want the line to be by cutting the end off.
The best way to do the design is to build it up line by line, I liked the idea I've seen elsewhere of making it look like the pattern is half on the biscuit, half off.
So there we go, wrapped in cellophane and with a ribbon they'd be lovely as a valentine's day gift. I also think they'd make beautiful homemade favours at a wedding... although I'm not sure I'd recommend it for a big one, not exactly quick and easy.