For Grandma’s doughnuts, mix butter, flour, sugar, nuts and lemon juice on a board until smooth. Roll out the dough to the thickness of the back of a two-knife, cut out slices and cut them in half. Preheat the oven to 160 degrees.
Place the halves of the dough discs on a baking tray lined with baking paper and bake until golden brown. Allow to cool, then spread each two halves with jam and assemble. Cover Omas Krapferln with chocolate glaze.