Well, first things first, we've been buying these 2lb bags of really nice small brussels sprouts at Costco. They seem to be pretty good.
Then we've been washing, cutting off the discoloured stalk end and removing outer leaves. Then also using a trick of my mother's -- cutting a cross into the stalk end 0.5-1cm deep (so if you look end-on you see an X) -- to make them cook more evenly (otherwise that's the densest part and doesn't cook as well as the head).
Theeeen, I've been *roughly* following Cook's Illustrated's cooking instructions doubled up (because they sounded close to what I remembered of Mum's and they're generally very reliable):
Bring 2lb brussels sprouts, 1 cup water, 1tsp salt to boil (medium-high) in ~4qt saucepan[*], turn down temp (I've been doing -> ~medium), put on lid firmly, let boil/steam/cook for 10 minutes--shake a couple of times to redistribute now and again during cooking (don't remove lid! They're steaming inside there).
My final (not called for by the recipe on C.I.) step is, after draining any remaining water (you could keep it for use in soup if you liked; it'll be very green and sprouty), to add whatever ungodly amount of butter you like (I think I added something on the order of 6/8 tbsp) and, if you like, sprinkle some nutmeg (ideally freshly ground) over them. Keep on (or return to) the heat to melt the butter and mix around well with a spoon to cover all the sprouts evenly with butter (and nutmeg).
The sprouts are braised, which is a remarkably good way to do sprouts.
2lb of sprouts sounds like a lot for 2 people, but there's some loss in the preparation stages (throwing away outer leaves, trimming stalks, etc.) and they're so bloomin' good that we ended up eating about 75% of them in the one sitting. So, we have fewer left-overs than I'd like, actually! =)
[*] Their recipe says 1/2 of each quantity and 2qt pan.