Blitz the flour and butter in a food processor to breadcrumbs. Add the icing sugar and pulse. Add the egg yolks and 1 tbsp water. Blitz until the pastry comes together into a ball. Wrap in cling film and chill for an hour.
Preheat the oven to 180°C/160°C fan/gas mark 4. Roll out the pastry and cut out 12 circles, using a ring cutter slightly larger than the indentations in your mince pie tin. Press the pastry into the tin, then fill each tart with a spoonful of mincemeat, taking care not to overfill. Bake in the oven for 15 minutes, until golden brown. Remove from the oven and leave to cool.
Add the gelatine to 50ml water and leave to dissolve. Put the egg whites and cinnamon in the bowl of a freestanding mixer, with the whisk attached.
Place the sugar and liquid glucose in a pan with 100ml water and heat over a gentle heat, stirring until dissolved. Bring to the boil, keeping a sugar thermometer in the syrup to check the temperature. When the syrup reaches 115°C, start to whisk the egg whites. When it reaches 120°C, remove from the heat and stir in the gelatine. Slowly pour the sugar syrup into the egg whites and continue whisking until cold, and the mallow is soft but holds its shape.
Put the mallow in a piping bag with a star nozzle attached and pipe individual swirls of the mallow on top of each pie.