Preheat the oven to 375°F (190°C). Have ready an 8-inch (22cm) pie pan with a removable bottom.
Cut the cold dough disc into two pieces, one slightly larger than the other (about ⅔ and ⅓ of the dough). Keep the smaller piece wrapped and refrigerated, and roll the large piece until it's about 2 inches larger than the base of the pie pan. Line the pan without stretching the dough, but letting it slide and pressing the sides, angles and bottom so it adheres well. If it's too soft, pop the pan in the freezer for 10 minutes before filling, while you roll the rest of the dough.
Roll the smaller piece of cold dough. Pour or spread the filling and smooth the top. Cover with the remaining dough, sealing the edges well. I like to pop it in the freezer for 15 minutes before baking, but it's not essential. Cold crusts bake better than ones that have softened a tad when handling them.
Prick the surface a few times with a fork to allow steam to escape. You can also brush with an egg wash (1 egg stirred with 1 tablespoon of water or milk) for a shinier top crust; I usually don't as the top will be covered with powdered sugar, but some people do it anyway.
Bake for 10 minutes, turn down the oven temperature to 350°F (180°C), and bake for another 15 to 20 minutes, until golden brown.
Let cool completely on a wire rack, remove from the pan, and sprinkle with powdered sugar to cover completely before serving. I like to bake it the day before, or several hours in advance, to allow the flavors to meld.