Add all the dry ingredients and spices to a large bowl and mix well to combine.

Grate over the orange zest and add the raisins, sultanas, and candied citrus peel. Mix to distribute evenly through the flour.

In a jug, melt the butter in the microwave, then add the buttermilk, vanilla, and egg yolk and whisk until well combined.

Pour the wet ingredients into the dry and mix until all the flour is absorbed and you have a thick, uniform dough.

Press the dough firmly into a lined 20cm x 20cm (8-inch x 8-inch) square baking dish and smooth the surface evenly.

To bake in an air fryer: Preheat to Bake at 180°C and bake for 30 to 35 minutes until golden brown. Insert a sharp knife into the centre and it should come out clean.

To bake in an oven: Preheat to 180°C / 350°F and bake for 35 to 40 minutes until golden brown. Cover loosely with foil from around the halfway point to prevent over-browning. The knife test applies here too.

Remove from the oven and allow to cool in the tin for 10 minutes, then turn out onto a cooling rack.

Once cool enough to handle, cut into strips. Cut seven strips in one direction, then cut each strip into thirds to make 21 rusks.

To dry in an air fryer: Preheat to Dehydrate at 73°C and dry for 5 to 6 hours.

To dry in an oven: Preheat to 90 to 100°C, preferably fan-forced, and line a large baking sheet with baking paper. Dry the rusks for 4 to 5 hours, turning them over halfway through. Turn the oven off and leave the rusks inside overnight. They should be completely dry all the way through before you store them.