Preheat oven to 220˚C. Grease a 12 cup muffin / cupcake tin.
In a large pan over medium high heat add a drizzle of olive oil. Cook the mushrooms with the smoked salt until golden brown. Toss in the thyme leaves and mix. Set aside in a bowl to cool.
In the same pan add a fresh drizzle of olive oil and the butter. When the butter begins to sizzle add the onions. Toss them well and cook until soft. Sprinkle over the sugar and begin to caramelise. Cook until a deep golden brown. Season and set aside.
Working quickly so that the pastry does not get warm, cut out rings of puff pastry that fit neatly into your cupcake tin. Place circles back into the fridge.
Line each bottom of the cupcake tin with mushrooms. Top with a little bit of the caramelised onion, and then finally a few shavings of parmesan.
Remove the puff pastry from the fridge and cover mushroom mix. Press down lightly especially around the edges. Using the tip of a small knife make a little hole in the centre of each pastry round for steam to escape.
Bake in the oven for 20-25 minutes until golden brown and the pastry is cooked through.
Place a cooling rack on top of the cupcake tin and using dishcloths carefully so you do not burn- flip the cupcake tin over. If you are not brave enough use a large spoon and with some confidence slip the spoon into each mold under the mushrooms and then flip them out.Serve straight away.