Season the beef fillet with salt, pepper, and oil. Sear in a hot skillet on all sides and set aside to cool

In a saucepan, melt butter, and add the mushrooms and onions. Cook at high heat until all liquid is gone; add the herbs, garlic, and base

Deglaze with the white wine and reduce the liquid. Then add the heavy cream and reduce until dry. Place in the food processor and purée until a coarse chop

Cut the puff pastry into 6 squares and roll the pastry a little on a floured surface. Then place the cheese, duxelles and meat in the middle of the pastry. Fold all the corners into the middle to cover the meat. Make a hole in the centre once you turn it over; this will allow the steam to escape when cooking

Egg wash the outside. Preheat oven to 425°F and bake for 20-25 minutes or until pastry is golden brown. Serve with your favourite brown sauce