I've seen this done in a couple of cabins. One was an older P&B with round loft joists adzed flat on top and where they lapped over the beams. I think they were spiked in place but they may have just been held there by the loft floor.
The other had about 50-60% of the joist above beam level and there were shallow drop in mortices in the beam. It also had a hand carved details on the summer beam and plaster ceiling (except where the roof leaked and it fell).
