Gluten free biscuits will not act in the same way as their gluten cousins. I have not added any gums, commonly seen in gluten free baking, to these biscotti and as such they are slightly fragile and crumbly. Take a little care when slicing the loaf and you will be rewarded with intact slices. Cooling the loaf in the tin is a critical step in making these biscotti work so don't skip it. It is the moisture trapped in the tin that allows the loaf to soften enough that it will slice without crumbling immediately.