Step 1

In a large mixing bowl, whisk flour, sugar, salt, chives, thyme and parsley in a bowl

Step 2

Once herbs are coated in flour and evenly dispersed, use a pastry cutter, or a fork to cut butter into flour mixture, forming pea-size crumbles

Step 3

Add water; work dough until flour and butter are incorporated

Step 4

Do not over mix

Step 5

Form the dough into a flat circle and wrap it in plastic wrap

Step 6

Chill in refrigerator for at least 20 minutes before using. While crust is chilling, make the filling

Step 7

Using a wet paper towel, “wash” mushrooms

Step 8

Slice them into ¼ thick pieces

Step 9

Melt butter in a heavy skillet

Step 10

Add onions and saute for 3-5 minutes on medium heat

Step 11

Add the mushrooms and increase heat to medium-high

Step 12

Cook mushrooms for 5-7 minutes until mushrooms are tender and most of the liquid has evaporated

Step 13

Season with salt and pepper

Step 14

Turn heat off and set aside. Preheat oven to 400° F

Step 15

On a lightly floured surface, roll dough into a 15-inch circle about ¼ inch thick

Step 16

Carefully transfer to a parchment paper lined baking sheet

Step 17

Spread the crème fraîche onto the rolled out crust

Step 18

Starting in the center work your way out, leaving a 2-inch border all around

Step 19

Using a slotted spoon, scoop the mushroom mixture out of the pan and gently place on top of the crème fraîche

Step 20

Top with gruyere and sprinkle with fresh thyme

Step 21

Fold the border up and over the filling, pleating as needed. In a small bowl, whisk the egg with 2 tablespoons water

Step 22

Using a pastry brush, brush egg wash over the dough rim

Step 23

Bake the galette for 45-50 minutes

Step 24

If the crust starts getting too brown, tent with foil

Step 25

Let cool on a wire rack for 5 minutes before slicing and serving.