There are several little platonic moments that you can have with your companions (Wicked Grace, of course, drinking Maraas-Lok with Bull, chess with Cullen, Val Royeux with Cole).
But Sera's cookies are unique in being able to be repeatable, platonic affection.
The first roof time is very sweet, because Sera's allowing herself to be vulnerable and share a very painful moment (my Inky instantly developed a fondness for raisin cookies, and I bet my Inky was also testing out all the Dalish recipes she had learned from her mother on Sera one by one until she found the right one that she could teach Sera to make). But after that, you can just run into the Herald's Rest and sit on the roof with Sera, and she won't make you talk, because you don't make her talk until she's ready, but you can just be there, sharing a little quiet moment with a friend.
I truly love having that in a game, a little quiet special moment with a friend and it's not tied to romance. It's special.













