muffins worked out very well with the Glutafin Fibre Mix (gluten-free). We've made these with non-gf plain flour before and if anything the Glutafin is better (now, there's a first!).
The carb count isn't pretty - I make it out at about 35g CHO each but a) they're big, though very light and airy so not fibre-filling and b) you could reduce the sugar somewhat though maybe not as much as usual given the tartness of rhubarb.
The crispy carmelised sugar top was a big hit and has a big bang-for-buck ratio for our 'taster'.
Oh, and I must credit the elder brother for this baking!