Preheat your oven to 180° C /160° Fan /Gas 4 /350° F.

Line several baking trays with baking paper. A standard sized tray will fit 8 biscuits and the recipe makes approximately 36, so you'll probably need to cook in batches. I bake 2 trays at a time.

Make the dough

Sift together the flour, bicarbonate of soda, and salt then set aside.

Beat together the sugar, butter, and vanilla until soft, ideally using electric beaters.

Beat in the egg along with one heaped tablespoon of the sifted flour mixture.

Switch to a spoon and stir in the remaining flour, making sure no dry flour is visible, followed by the mincemeat and chopped nuts. The mixture will be quite stiff but this is normal.

Form the biscuits

Take 20 g of the mixture (use scales for accuracy) and roll into a ball between your palms (lightly wet your hands if necessary) then place it on a baking tray.

Make 7 more balls and place on the tray, spacing them well apart as the biscuits will spread.

Dip a fork in a little extra plain flour to stop it sticking, then press down on each ball to make an even disc approximately ½ - 1 cm thick.

Repeat with 8 more balls of dough, placing them on a second baking tray.

Bake the biscuits

Put in the oven and bake until golden brown and cooked all the way through which will take approx. 12 - 15 minutes. Depending on how thick you made them, this should give you biscuits crisp on the outside, slightly soft in the middle: cook for a few minutes longer for a completely crispy biscuit if necessary.

Use a palette knife or similar to remove the biscuits from the trays and transfer to a wire rack: they will still feel a little soft but will firm up as they cool.

Leave until completely cold, meanwhile making more trays of biscuits with the remaining dough.

Dust the cold biscuits with sifted icing sugar and store in an airtight container.

Should keep for up to a week, although longer baked, crisper biscuits may keep for up to 2 weeks.