Preheat oven to 160°C/325°F/Gas Mark 3. Place bread in a food processor and blitz to produce coarse crumbs (or you could grate it on a coarse grater). Place 50 g (1 ⅔ oz) of the butter in an ovenproof frying pan and heat over a moderate heat until bubbling. Add breadcrumbs and toss continuously until golden and crisp. Tip onto kitchen paper and leave to cool.
Wipe out pan and place it back on the heat. Add remaining butter and melt. Add feijoas and cook for 1 minute over a moderate heat, turning continuously. Add ginger and honey and bring to the boil, then add lemon juice and bake for 15 minutes. Remove and leave to rest for a few minutes before sprinkling with breadcrumbs and serving with a scoop or two of vanilla ice cream.