Combine the ingredients for the pumpkin spice mix in a large bowl. Tip the pumpkin purée onto a sheet of kitchen paper or muslin cloth and spread out slightly. Put another towel on top and set aside to soak up the excess moisture.

Tip 1 tbsp of the spice mix into the flour along with 1/2 tsp fine salt and combine. Beat the butter and brown sugar together in another bowl using an electric whisk for 2-3 mins until light and fluffy. Mix in the egg. Beat in the pumpkin purée and vanilla, then fold in the flour mix until just combined into a soft dough. Chill for 1-2 hrs to firm up slightly.

Line a large baking tray with baking parchment. Roll about 30g of the dough into a ball using damp hands, then flatten slightly into a disc. Put on the tray, then repeat with the rest of the dough (you should get 10-12). Chill for at least 1 hr, or freeze overnight.

Heat the oven to 200C/180C fan/gas 6. Line two or three large baking trays with baking parchment. Mix the caster sugar with most of the remaining spice mix, reserving 1/2 tsp. Flatten the dough discs a little more between your palms, then push both sides and the edge into the spiced sugar mix to coat. Transfer to the trays, spacing them well apart. Bake for 12-14 mins, flipping the trays around halfway through, until the middles are puffy and the edges just golden. Cool on the trays for 10 mins, then put on a wire rack to cool fully. Will keep in an airtight container for three days.

For the filling, beat the butter and soft cheese until smooth. Beat in the icing sugar and the rest of the spice mix until pale and fluffy. Spread the filling over the flat sides of half the cookies, then sandwich with the other cookies. Will keep chilled in an airtight container for a few days.