Aachener Printen (Aachen spiced gingerbread slabs)

Step 1: Warm 9 oz sugar beet syrup, 1 ¾ oz dark brown sugar and 3 tbsp water in a pan over a low heat, stirring, until the sugar dissolves. Do not boil. Cool to lukewarm, about 20 minutes.

Step 2: Mix 1 ⅛ lb plain flour, 2 tsp ground cinnamon, 1 tsp ground aniseed, 1 tsp ground coriander, ½ tsp ground cloves, ½ tsp ground cardamom and ½ tsp ground allspice in a large bowl. Pour in the lukewarm syrup and knead into a stiff, heavy dough.

Step 3: Knead in 3 ½ oz brown rock sugar and 1 ¾ oz candied orange peel. Wrap the dough well and leave it at cool room temperature overnight, at least 12 hours; it will firm up and the spices will deepen.

Step 4: Next day, heat the oven to 375°F (350°F fan) and line two trays with baking paper. Dissolve ⅛ oz potash (potassium carbonate) in 1 tbsp cold water.

Step 5: Knead the potash solution into the dough for 2–3 minutes until evenly streak-free; the dough will feel stiff and slightly sticky. Warm it briefly in your hands if it is too hard to work.

Step 6: Roll out on a lightly floured surface to 6 mm thick and cut into 2.5 x 8 cm slabs. Place on the trays 2 cm apart.

Step 7: Bake one tray at a time for 12–15 minutes, until puffed, deep brown and firm at the edges. They will still feel slightly soft in the middle.

Step 8: Meanwhile boil 1 ¾ oz caster sugar with 3 ½ tbsp boiling water for 1 minute to a clear syrup. Brush it over the Printen straight from the oven to give them a shine.

Step 9: Cool on a rack. For hard, snappy Printen store them in an open tin for 2 days; for softer ones, store airtight with a slice of apple for a week.