Decadent and delicious, this custardy pie features leafy green spinach and fresh mushrooms. Serve it for brunch with fruit or as a filling dinner entree with salad. If time is short, forego making your own crust. Keep it simple and buy prepared dough or a frozen shell.
For Pastry Dough
4 ounces butter, chilled and diced
1¼ cup all purpose flour
½ teaspoon kosher salt
5 tablespoons cold water
1 tablespoon butter
¼ cup finely chopped onion
2 cups sliced assorted mushrooms
4 packed cups baby spinach
3 large eggs
¾ cup half & half
½ teaspoon kosher salt
¼ teaspoon fresh cracked pepper
1 cup shredded mozzarella cheese
2 heaping tablespoons shredded Parmesan cheese
MAKE THE DOUGH
Combine the chilled butter (see note), flour, and salt in a bowl and then use your fingers to pinch the butter into the flour until it is of a pebbly consistency. Sprinkle the water on top and toss the flour mixture to distribute the water. Begin to form the dough into a ball, working as little as possible, just enough so that the ball holds together. Place on plastic wrap and press into the shape of a disk.
Wrap disk in the plastic and place in the refrigerator for at least 30 minutes.
Remove the dough from the refrigerator and roll out into a 12 to 13- inch circle. Gently place the dough into a 10-inch tart pan with a removable bottom. Carefully lift the dough and work it into the edges of the pan, trying not to stretch the dough. Cut off the excess dough by rolling your pin over the lip of the tart pan and then smooth the edges with your fingers. Place the pan into the refrigerator until the filling is prepared.
To quickly chill the butter, shred cold butter on a large grater and place it in the freezer. Within 15 minutes you will be ready to combine it with the flour. And always remember: the less water you use in pastry dough, the better.
PREPARE THE FILLING
Preheat oven to 375°F. If you have one, place a baking stone in the oven. Place the butter in a hot skillet. When the butter has melted, add the onion and mushrooms and sauté for approximately three minutes. Add the spinach and allow it to wilt as you stir it into the mushroom mixture. After approximately two minutes, remove the vegetables onto a plate lined with paper towels. Carefully press with another paper towel to remove excess moisture.
Whisk the eggs and the half & half in a medium bowl. Add the vegetables to the egg mixture and season with the salt and pepper. Combine the cheeses and distribute into the bottom of the pastry shell. Carefully pour the egg mixture over the cheeses. Use your fingers to distribute the mushrooms and spinach to the edges, if needed.
Place on the baking stone in the hot oven and bake for approximately 30 minutes, or until a knife inserted in the middle comes out clean. Cool on a wire rack and then remove from the tart pan and onto a serving platter.