Step 1

Warm half of the olive oil and the butter in a pan over a high heat. When hot, add the mushrooms, then season and cook for a few minutes until golden. Spoon into a large mixing bowl.

Step 2

Return the pan to the heat, then add the leek and parsnip and cook until golden and softened, reducing the heat if they begin to catch on the bottom of the pan.

Step 3

Stir in the oregano, tomato puree and flour to make a thick paste. Pour in the wine and mix well to combine. When the wine starts to boil, continue stirring for another minute, then pour the mixture into the mixing bowl with the mushrooms. Set aside to cool completely.

Step 4

Butter 6 mini pudding basins or dariole moulds that will allow you to fit in a single layer in your slow cooker. Line the bases with a small square of greaseproof paper. Butter six 15 x 15 cm squares of tin foil and set aside.

Step 5

For the pastry, mix the flour and a large pinch of salt in a large mixing bowl. Add the suet and mix well. Mix in the mustard and enough cold water to make a soft dough. It is best to do this with your hands.

Step 6

Take a quarter of the dough, turn out onto a lightly floured surface and roll out to a 5mm thickness. use one of the basins to cut out 6 rounds and set them aside for the pie lids.

Step 7

Roll the remaining dough out to 5mm thickness and cut into 6 large rounds - about 13 - 15 cm across. Use these to line the prepared tins, pushing into the base of each one. Leave about 1cm hanging above the top of the basins.

Step 8

Spoon the cooled filling into the lined basins. Place the lids on top and fold the overhanding dough over the edges to seal. Cover with the foil, making a pleat in the centre to allow room to rise. Tie around the top of the basins tightly with string to stop any water getting in.

Step 9

Place the basins into the slow cooker dish. Carefully pour enough boilim water around the edge to come upto one third of the way up the side of the basins. Cover with the lid and cook on high for 4 hours, or on low for 8 hours.

Step 10

Remove the basins from the slow cooker and leave to stand for 5 mins. Run a sharp knife around the edge of the pies and invert onto a plate to serve.