The short version: mandel bread is softer, made with oil, and Ashkenazi Jewish. Biscotti is harder, drier, and Italian. Both are twice-baked, both are built for dunking, and they are probably related.
Biscotti is the comparison we reach for constantly, because it is the only twice-baked cookie most people have met. It is a good starting point. It is not the whole picture.
The differences, one at a time
Texture
This is the one people notice first.
Classic Italian biscotti is hard. Traditional recipes use little or no fat, so the second bake leaves something closer to a cracker than a cookie. Biscotti needs the dunk.
Mandel bread is different. We describe ours as a softer biscotti: a delicate crunch on the outside, softer on the inside. Mandel bread does not need the dunk.
Fat
This is what causes the texture difference.
Traditional biscotti is nearly fat-free. Mandel bread uses oil. The oil interrupts the drying that the second bake would otherwise finish, so you get a cookie that keeps well without going rigid.
There is likely a practical reason for the oil, and it is not about texture. Many Ashkenazi households kept kosher, which means no dairy at a meal with meat. A cookie made with oil can end any meal. A cookie made with butter cannot. So the softness of mandel bread is, at least in part, a consequence of kosher law.
Shape and slicing
Both start the same way. Bake the dough as a log, slice it, bake the slices again.
Biscotti tends to be cut thin, on a sharp diagonal, and uniformly. Mandel bread slices are usually thicker and less regular, because they were cut in home kitchens by people who were not trying to match a bakery case.
Flavor
Biscotti leans toward anise, almond, and vanilla.
Mandel bread traditionally uses almonds, which is where the name comes from. But it drifted early and drifted everywhere. Chocolate chips, cinnamon sugar, dried fruit, walnuts, citrus.
Origin
Biscotti is Italian, from Tuscany. The word means twice-cooked.
Mandel bread is Ashkenazi Jewish, from Eastern and Central Europe. Mandelbrot is Yiddish and German for almond bread.
Are they actually related?
Probably. No one can prove it.
The usual theory: the Jewish community in Piedmont, Italy encountered the twice-baked technique and carried it east as families moved. Over a couple hundred years it became mandelbrot. The timeline works, and the two cookies are clearly cousins. But food rarely leaves a paper trail, so it stays a theory.
Which keeps longer?
Biscotti, technically. Less fat and less moisture means less to go stale.
But mandel bread keeps a long time too. That is the whole point of the second bake. It travels without turning to crumbs, and it was made by people who carried food places. Grandma Jeanne packed her suitcase with desserts instead of clothes so she could share them wherever she went, and the second bake is why that worked.
So which is better?
We make mandel bread, so take this for what it is worth.
Biscotti is better if you want something rigid to stand in an espresso. Mandel bread is better if you want a cookie that does not need the dunk.
The honest answer: they are cousins, they solve the same problem, and the one you prefer is mostly the one you grew up with.
Frequently asked questions
Is mandel bread the same as biscotti?
No, but they are closely related. Both are twice-baked cookies made for dunking. Mandel bread is softer, made with oil, and Ashkenazi Jewish. Biscotti is harder and Italian.
Why is mandel bread softer than biscotti?
Mandel bread is made with oil, while traditional biscotti uses little or no fat. The oil keeps the cookie from drying out completely during the second bake.
Why does mandel bread use oil instead of butter?
Likely because many Ashkenazi Jewish households kept kosher, which prohibits dairy at a meal containing meat. Oil makes the cookie pareve, so it can be served after any meal.
Which came first, biscotti or mandel bread?
Biscotti is older. One theory holds that the twice-baked technique traveled from Italy to Eastern Europe through Jewish communities, where it became mandelbrot, though this cannot be proven.
Can you dunk mandel bread?
Yes, and it holds up well in coffee or tea. Unlike biscotti, it does not need the dunk.
Try it yourself
Grandma Jeanne made mandel bread her whole life. She baked well into her nineties and lived to 102. Four generations later we bake her recipe by hand in South Denver, in full-size slices and in a bite-size version we call MandelBites.
Read more about what mandel bread is, or see the gift boxes.