Sift the flour, sugar, salt, and baking powder into a large bowl.

Cut the cold butter into 1/2 inch cubes and add it to the flour mixture. Use a pastry cutter to cut the butter into the flour mixture until a coarse meal forms.

In a small bowl, combine the egg and the vanilla extract. Stir the egg mixture into the flour mixture with a fork until a dough begins to form. Knead gently to fully combine, then wrap the shortcrust pastry tightly in plastic wrap and chill in the refrigerator for at least one hour.

Preheat oven to 350 F. Grease and line a 9-inch springform pan with parchment paper.

In a large mixing bowl using a whisk, mix the eggs and sugar until fully combined. Add the cornstarch and vanilla extract and stir to combine. Then add the oil and lemon zest and mix again.

In the bowl of a stand mixer, using the whip attachment, whip the heavy cream until soft peaks form.

Fold the whipped cream and quark into the egg mixture little by little using a large rubber spatula until you have achieved a smooth consistency and no lumps remain.

Place the dough on a well-floured work surface. Sprinkle flour over the top of the dough and the rolling pin, then roll the dough out until you have a 12 inch circle. Trim the dough to make a nice even circle.

Place the rolled dough into the pan and press it into place. You should have roughly 1 inch of dough going up the sides of the pan.

Pour the cheesecake filling into the pan and tap the filled cake pan several times on the counter to ensure that you have removed any large air bubbles.

Bake the cake in the lower third of your preheated oven for 70-90 minutes. Remove the cake from the oven and let it cool fully before removing the ring of the springform pan.

Dust the cheesecake with powdered sugar and/or decorate with berries before serving.