1. Separate the egg whites and yolks. Place the whites in a metal mixing bowl (good for whipping). Allow the whites to warm to room temperature - about 30 minutes. This makes it easier to get stiff peaks.
2. Preheat the oven to 350°F (180°C).
3. Fit the pie crust to a 9 inch cake pan, pushing on the sides and bottoms so it adheres well.
4. In a mixing bowl, stir together the cake flour and sugar until well blended. Add the fromage blanc or quark, heavy cream or crème fraîche, egg yolks and lemon juice. Stir until well blended. Don't worry if it is a little lumpy, you can blend it a little more with the hand mixer in a minute.
5. Using a hand mixer equipped with a whisk, whip the egg whites until stiff peaks form. You can then use the mixer to completely blend the cheese and egg mixture if it needs it. Stir in about a third of the egg whites into the cheese and egg mixture to lighten it. Then, using a spatula, gently fold the rest of the egg whites into the mixture. It takes about 15 to 20 folds - don't over do it.
6. Pour the batter into the prepared pie crust and place in oven. Bake for 40 minutes at 350°F (180°C).
7. Remove cake from the oven and allow to cool for 5 minutes. Place a wire cake cooling rack on top of the cake and flip it over. Remove the cake pan and allow the cake to cool for 20 minutes or so, then flip it back over onto a serving plate and allow it to finish cooling. These acrobatics help to keep it from deflating.
8. Cool completely, cover with plastic wrap, and refrigerate until serving time.
9. To serve, sprinkle with powdered sugar.

Makes 8 servings.

* A slightly sweetened pâte brisée crust goes well with this.