Heat the oven to 180C/gas 4. Line two muffin trays with paper cases or squares of baking paper.
In a large bowl, beat the butter and sugar with an electric beater until pale and fluffy.
Combine the almonds, flour, mixed spice, baking powder and salt in a bowl, then sift it on top of the creamed butter and sugar. Add the orange zest, 3 tablespoons of the juice and the eggs to the bowl as well. Beat everything together until you have a thick batter, then stir in the dried fruit, cranberries and apple.
Dollop the mixture into the muffin cases so they’re three-quarters full. Bake for 35 minutes, then turn down the heat to 160C/gas 3 and bake for a further 20 to 25 minutes, until the muffins are well risen and golden, and a skewer inserted into the centre comes out clean.
Leave to cool in the tin for 15 minutes, then remove to a rack to cool completely.
Gradually mix the icing sugar with 4-5 teaspoons of the orange juice to make a thick icing. Spoon into a piping bag with a round nozzle, or into a sandwich bag, snipping off one corner. Pipe crosses onto each muffin, dust with extra icing sugar and leave to set.
Buckwheat, despite its name, is not related to wheat at all and is totally gluten-free. The flour has a light nuttiness. You’ll find it in most supermarkets and health food shops.