Makes 4-6 servings
Roll out pastry to 12” diameter. Refrigerate to rest.
Meanwhile, heat olive oil in a sauté pan over medium heat. Add onion and cook until translucent, about 5 minutes. Add mushrooms and thyme, cooking until browned. Season with salt and pepper. Set aside to cool.
Take pastry out of the refrigerator. Spread crème fraiche onto pastry, leaving a 2” diameter border around. Spread mushroom mixture on top of the crème fraiche. Top with the shredded gruyère.
Working all the way around, fold the border up and over the filling, pressing the dough together where it overlaps.
Once finished, place the galette back into the refrigerator to rest.
Light the Cru oven.
Before baking, brush the pastry with a beaten egg.