I never throw away dry buns, bread or bunt cake. Instead I cut them in smaller pieces and let them dry out completely inside the oven. Just heat the oven to 70°C / 160°F and leave it for a few hours. You may have to adjust the temperature a bit depending on your oven. Like this you may transform old bread into rusks and croutons or like in the picture above, dry buns into lovely saffron biscottis.