Any unsalted nuts are fine, though I'm not sure I'd give a whole Brazil nut every day! You don't want to spoil her appetite for her regular hamster food
They're quite easy to break - perhaps you could give her a quarter a day?
Alternatively, make her work for it! Inky has found Brazil nuts and walnuts in shells a bit too hard to get her teeth through, but hazelnuts are a good size and she can eventually get through the shell - it takes a few days but it clearly keeps her occupied as we have several hazelnut shells covered in teeth marks with a hole at the top where she has eventually managed to work it through
