In a small mixing bowl, whisk together eggs and ice water. Set aside.

In the bowl of a food processor, briefly pulse flour and salt to combine. Add butter and pulse until the mixture resembles coarse meal. (To make by hand: In a bowl, mix flour and salt. Add very cold butter and use your hands to crumble it into the flour until the bits of butter are about the size of peas. This will take about five minutes.)

Add egg mixture and pulse until a dough forms (or stir by hand).

Divide dough in half and place in two separate zip-top bags. Refrigerate 25 minutes (a bit longer is fine too).

Take one portion of dough and place it on a lightly floured surface. Roll it out to fit the 14-inch quiche pan, placing it over the pan and gently pressing it into place. Trim any extra dough hanging over the sides. Repeat with the second portion of dough.

Preheat oven to 350 degrees Fahrenheit. Line the bottom of the crusts with parchment paper and place uncooked beans on top to keep the bottom of the crusts from puffing up during baking. Bake seven to eight minutes.

Remove the beans and parchment paper and bake another five minutes. Set crusts aside.

In a skillet, heat butter and oil. Add shallots and sauté five minutes on medium-low heat, until soft and translucent.

Add mushrooms and sauté three minutes. Turn off heat. Add spinach and stir, allowing the residual heat to wilt the spinach. Set aside.

In a mixing bowl, whisk together eggs, heavy cream, salt, pepper, and nutmeg (if using). Set aside.

Place the baked crusts on a baking sheet (to catch drips during baking). Divide the prepared filling between the crusts.

In each quiche, sprinkle 1/2 cup mozzarella on top of the filling.

Using a ladle, slowly add the custard to each quiche, dividing it between them. Sprinkle one tablespoon goat cheese over each.

Bake 30 minutes, or until crusts are light golden brown and centers are set but still somewhat soft and a little jiggly. A toothpick inserted at the center should come out clean.

Transfer to a cooling rack. Serve slightly warm or at room temperature.