Put the flour, salt and sugar in a food processor. Add cubes of cold butter and pulse 7-8 times to form small beads in the flour. Check the uniformity of the flour mixture and cut any large pieces of butter with a knife. Pour water and pulse 7-8 times to just combine the ingredients. Dump the mixture onto a cold work surface and lightly knead with heal of your palm for 2 minutes. Be careful to not overwork the dough (good dough is crumbly and cold). Collect the dough and tightly wrap in plastic. Refrigerate the dough for at least 30 minutes.

Preheat the oven to 175°C / 350°F and refrigerate an 8-inch tart pan until use. Remove the dough from the refrigerator and leave at room temperature for 5 minutes. Place the chilled pastry dough on a lightly floured work surface and fold it 2-3 times to make it pliable. Dust some flour on a rolling pin and begin rolling the dough from the center to the edge. Turn the dough 90 degrees after each rolling action. Continue to roll and turn, till the dough is an even disc with 10-inch diameter. Brush off any excess flour from the dough and roll the dough onto the rolling pin. Hold the rolling pin on top of the pan and unroll the dough leaving 2-inches outside the pan. Gently, push (not press) the dough into the corners. After the dough properly covers the inside of the pan, trim the excess dough and chill the shell for 10 minutes (save the extra dough for later use). Gently prick the center with a fork a few times and line the chilled raw tart shell with a piece of parchment paper (app. 15-inch diameter). Fill with dry chic-peas or any heavy beans and bake the shell until light brown, about 20-22 minutes. Remove the chic-peas and parchment paper and wait for the shell to cool a little. Check for any cracks or holes in the shell and patch with tiny pieces of the remaining dough.

Reduce the oven temperature to 120°C / 250°F. Melt the butter in a saucepan and cook the mushrooms until tender, 5 minutes. Remove the mushrooms from the pan and place on a kitchen-paper to dry. Whisk together the milk, cream and eggs to make a homogenous mixture. Strain the mixture to remove the egg fibers and lightly season with salt and pepper.

Place the tart in the pan and evenly layer the mushrooms and cheese in the tart. Pour the milk-egg custard in the tart and carefully transfer the quiche to the oven. Bake until the custard sets, about 25-30 minutes.

Remove from the oven and let the custard firm for about 10-15 minutes. Transfer to a cutting board and slice the quiche using a serrated knife and serve immediately.

Variation: To alter the filling, substitute mushrooms with fried chicken or use in combination with greens like spinach and broccoli.