These admirable buns have much in common with krantz cakes, babka and cinnamon rolls. That said, while not lean per se, they are leaner than most of those. They are sweet without the toothache, kept keen by the bite of seasonally appropriate marmalade and grounded by a savoury smudge of tahini. Cocoa nibs bring texture to the filling, along with a memory of those sliced chocolate oranges my older brother used to like.
And a couple notes on that filling. For the sugar, use the darkest you can find. Muscovado, a semi-refined cane sugar, is particularly appreciated here; its bittersweet depth adds dimension to the filling, and its colour brings that much more contrast between the filling and dough. Instead of cocoa nibs, toasted nuts would do nicely.