In a small pot or bowl combine the chicken seasoning. Lay out the thighs and evenly sprinkle the seasoning over both sides of the thighs.
Heat 1 tbsp oil in a large pan over medium-high heat. Once hot, add the thighs and fry both sides for around 4-5mins, until lightly charred and just about cooked right through the centre (they will carry on cooking as they rest and when in the pies). If they start charring too aggressively just lower the heat slightly. Remove and place on a plate to one side. Lower the heat to medium.
Add the chorizo to the pan and fry for a couple of minutes until it starts to leak out fat and crisp very slightly. Add the onion, celery and garlic and continue frying until it all softens right down and the chorizo crisps up a little more. Don't rush this - you need to render out the fat from the chorizo and sweeten/soften the onion.
Stir in the flour to create a roux, then gradually add the stock, whisking as you go to avoid lumps. Stir in the crème fraîche, then stir in the tomato puree, lemon juice, parsley and the resting juices from the chicken. Simmer and stir somewhat frequently for 10 minutes until the sauce is nice and thick.
Meanwhile, dice the chicken into small pieces (see video for reference) then stir into the sauce. At this point the sauce should be pretty thick and not runny at all. Leave to cool and preheat the oven to 190C/375F.
Slice 12x 10.5cm/4" circles from the shortcrust pastry. Grease the tin holes then place in the pastry, ensuring you gently press it against the tin, creating 12 'cups'. For the lids, you'll need to cut out 12x circles the same size as the rim of the holes (should be 7.5cm/3"). You can either use puff pastry, or roll out the excess shortcrust pastry and use that.
Spoon the filling into the cups, then top with the lids and use your fingers to gently press around the edges so it sticks to the base. Brush the tops with egg wash, slice in a couple of small steam holes then bake in the oven for around 25 minutes until deep golden and crisp.
Leave to rest for 5 or so mins (the filling will be pretty hot) then tuck in and enjoy!