Issues with part-time manager

[VagueAmbition]

I work in a fairly small team, and my job is full time. About a year ago, my manager moved to working part time (2.5 days a week), for personal and health reasons.

She likes to have a very hands on role with all projects, and as a result, we've cut back the number of projects we undertake. The result is that I don't really have enough to do. I've mentioned this a couple of times before, but she tends to laugh it off - she's very busy during her working days, and I think she can't see that I'm not particularly occupied, partly because naturally I am busier on the days she's in. (I'm also somewhat overqualified / overexperienced for the role as originally conceived, so am able to do it quicker than might be expected.)

This may sound great, but in reality, I'm pretty bored and frustrated.

Does anyone have any suggestions for sorting the problem out? Because of the way things are set up, there isn't another senior person I can speak to, which might be an obvious solution.