The recipes for marzipan confections in that book use pure almond paste, which is high-carb and filled with sugar. The other low-carb cookbook is a Swedish book, Bakglädje med LCHF by Annika Rogneby (yes, I love to collect cookbooks in different languages, well, no wonder, I’m a linguist…).
In a medium bowl, combine the almond flour and the sweetener. Sift the almond flour and the sweetener for the best and smoothest result. Add the egg white and the almond extract. Knead until smooth. This shouldn’t take more than a minute. Shape and mold as you wish. Wrap the leftover marzipan in a plastic wrap to prevent it from drying.
My sugar-free, low-carb marzipan experiment was a great opportunity to explore more of this Zsweet sweetener. For the first experiment, I used just some 3.5 oz (100 g) of both almond flour and Zsweet, one egg white and a couple of drops bitter almond flavor. The texture was perfect, but the taste was far too sweet.
Dust the surface with icing sugar, then knead the marzipan briefly with your hands to a smooth dough. Don't overdo it as the paste can get greasy. Add a bit more icing sugar if it seems too wet. Shape into a ball, then wrap and keep in a cool place until ready to cover the cake. Can be made up to 2 days in advance.