Blind bake the crust. *Before blind baking the crust, make sure the dough has been chilled for at least an additional 10 minutes after being molded into the baking pan.*Dock the pie crust to release steam and to prevent uneven baking. Line the chilled crust loosely with parchment. Fill the lined parchment with pie weights, uncooked rice, or dried beans to prevent crust from puffing up. Bake for 10-15 minutes, or until the crust starts to turn golden brown. Remove the parchment lining and pie weights. Continue baking for another 8 minutes until the center no longer look raw. Set aside and let cool.
Turn oven to 375°F.
Cook the mushrooms and leek. In a saute pan with a little bit of oil, cook down the vegetables until tender and wilted. Season with a generous pinch of salt and pepper. Transfer veggies to a plate with paper towels to soak up excess moisture. Set aside and let cool.
Make the filling. Combine the beaten eggs, milk, cooled veggies, and 5 oz. of parmesan cheese. Pour the mixture into the cooled crust and spread evenly. Sprinkling remaining 1 oz. parmesan cheese over the top.
Bake. Bake the quiche for 40-50 minutes. When the center is set and jiggles slightly, it is done.
Serve and enjoy! Quiche is best served warm. So cut and enjoy once it cools slightly.