Facing the same opposition on successive weekends is a challenge sides only encounter in European competition and Moffat admits it's one that really whets the appetite.
"We're certainly looking forward to those games against Castres. I really like the back-to-back element as well," said Moffat, whose side travel to France on Saturday, December 11 before the return leg at Murrayfield the following Sunday.
"It's something else about the Heineken Cup which is a bit different and a bit special.
"You play a team one week and then the next so it's not a case of waiting three or four months and that means you've got to be smart. It brings different challenges and that's fantastic."
Edinburgh head into Round 3 without a Heineken Cup win this season having lost two close encounters to Cardiff Blues and Northampton Saints.
An away trip to a typically tough French venue wouldn't be most side's preferred option as they chase their first victory but travelling away from home holds no fears for Moffat and his men.
"Away form is a strange one. I don't think it's as difficult for us as it is for some other teams because of the way we view away games," added Moffat.
"Two years ago especially, we had a very good away record.
"We should be okay away from home because we approach games very similarly to how we do at home. We don't change dramatically how we play.
"I think a lot of teams struggle in away games because the mindset is conservative in compared to what it is at home. Ours isn't so we'll approach away games very similarly to home games.
"We'll certainly not go out to try and restrict the opposition or calm things down in the first 20 minutes - we'll play.
"We know Castres as we played them three years ago in the Heineken Cup and we beat them then. Castres are the only French team we've beaten away from home so we're pretty familiar with them.
"But you never know - by the time we play them in December, anything could be happening."