01 -
Get your oven to 350°F (180°C) and lay some parchment on your baking tray so nothing sticks.
02 -
Melt butter with olive oil in a big pan over medium heat. Toss in the diced onions and give them about 5 minutes, stirring now and then till they're soft and clear but not browned.
03 -
Add the minced garlic and sliced mushrooms to the pan. Keep moving them around and cook for about 8 minutes until the mushrooms look browned and all the water they gave off is gone, which builds up the flavor.
04 -
Sprinkle in the thyme, salt, and pepper. If you want, pour in the white wine next and let it bubble away while you scrape the brown bits stuck to the pan. Lower the heat after that.
05 -
Turn the heat down, then mix in the cream cheese, Parmesan, and a little Dijon if you’re using it. Stir until smooth and melted. Take it off the heat and fold in the Gruyère cheese until the mixture thickens and feels creamy.
06 -
Beat one egg quickly and stir it into the cheese and mushroom mix to hold everything together. Let it cool a bit so you can handle it without it being too hot.
07 -
Dust your rolling surface with some flour, then unroll that thawed puff pastry. Cut eight strips diagonally along each long edge but leave the middle part clear to hold the filling.
08 -
Spoon the cooled mushroom-cheese mix right down the center. Make sure it stays away from the strips. Fold in the pastry ends and then fold the strips over, one side then the other, to make a braid.
09 -
Using the parchment paper, move the braid to your baking tray. Beat the leftover egg and brush it all over the braid to get a shiny golden top.
10 -
Pop it in the oven and bake for 20 to 22 minutes till it puffs up and turns golden. If it’s browning unevenly, spin the pan around halfway through.
11 -
Let the braid sit for about 10 minutes so the filling firms up. Finish it off with a sprinkle of fresh parsley and serve it warm for the best taste and feel.