Borrelnootje

A borrelnootje (Dutch pronunciationⓘ; English: roughly "cocktail nut") is a nut (often a peanut) with a crispy coating surrounding it, usually with a herbal flavour.

In the 1950s, the company Go & Zoon (later Go-Tan) made peanuts with a crispy outside.

[2] This family-owned company introduced the nuts from Indonesia, where it is known as katjang pedas (spicy peanuts).

Calvé paid patent rights to Go-Tan for the idea of mass-producing the nuts, whilst Duyvis invented their way of production.

This phenomenon could be a result of dough surrounding the nut rising, or due to moisture in the dough evaporating causing a decrease in volume.