Does it have to be in Dublin? We met Benoit Lorge recently at a market and sampled some of his chocolates. Gorgeous. He runs courses for children too if anyone is interested. Nice guy. Check out:
We used Lily O'Briens chocolates for our wedding. Gorgeous! They are based in Newbridge Co. Kildare, handy enough for South Dublin, but I think you can order them on-line as well.
My friend got married last year and she made her own favours using love heart sweets tied up in little net parcels. Time consuming I know, but she roped in a few helpers.
Not chocolates but we used www.clickthecookie.co.uk to get personalised fortune cookies. They went down very well, a different twist on edible favours.