Melt (or brown) the butter and fry the shallots until fragrant and golden. Add the mushrooms. I didn't cut up my mushrooms as they were pretty special. I wanted them whole.
When the mushrooms have cooked and are golden as well, add in the kale and stir as you cook until wilted and bright green. Add thyme leaves and seasoning to taste. Cool this mixture completely before proceeding.
Preheat the oven to 180°C and get a flat oven tray ready.
Roll the pastry out with a dusting of flour and divide into two equal pieces (though one can be slightly larger if it happens!) I had two pieces 20cm wide each x 30cm long approximately. Place the largest piece onto a sheet of baking paper and transfer to the oven tray.
Place the cheese into the Thermomix bowl and mill 10 sec/speed 8.
Brush the edges of the base piece of pastry with egg wash. Put the grated cheese into the middle of this pastry sheet. Top with the cold mushroom mixture. Cover with the other piece of pastry and bring the bottom edges up and over the top and pinch together to seal well.
Brush with plenty of egg wash, slash some vents across the top and sprinkle with sesame seeds.
Bake 30 minutes until golden and fragrant. Turn half way through if necessary to get an even finish. Serve hot or cold sprinkled with a few fresh thyme leaves!