[Leibniz butter biscuits by Hermann Bahlsen, 1891] "Hermann Bahlsen not only invented the shape of the biscuit, but also introduced the word "Keks" into German, deriving from the English word "cakes". At the end of the 19th century it was all the rage to name products after famous people. Since the biscuits were made in Hanover, the obvious choice was to name them after a famous person from the city: The man chosen was the mathematician Gottfried Wilhelm Leibniz, who, among other things, developed differential equations."

p.s. You can recognize a real Leibniz biscuit by its edges. The edge of the biscuit has 52 "teeth", if there is one more or less, it's a fake.

There's more where that came from at Monuments of German design at the Goethe Institute