Crust:

Cup of Yum
1. Preheat the oven to 180°C/ 350°F. Line the base of the springform with parchment paper.
2. Crush cookies: Place the butter cookies/graham crackers in a food processor and process until you have fine crumbs. Alternatively, you could place them in a freezing bag and crush them with a rolling pin.200 g crushed butter cookies or graham crackers/ 7 oz
3. Melt the butter and mix it with the crumbs. Press the mixtures into the prepared springform.100 g unsalted butter/ 3.5 oz/ scant ½ cup
4. Bake for 10 minutes in the preheated oven.

Streusel:

1. Make the streusel now, so you will not have to clean the food processor twice. Place the cold butter and butter cookies/graham crackers, flour, brown sugar, and cinnamon in the food processor. Process until the mixture starts forming large crumbs. Alternatively, mix with your hands until you get the crumbs. Transfer to a bowl.Scrape the food processor as well as you can; there is no need to wash it before making the filling.60 g unsalted butter/ ¼ cup 50 g crushed butter cookies or graham crackers/ 1.7 oz/ ½ cup + 75 g all-purpose flour/ ⅔ cup + 50 g brown sugar/ ¼ cup + ½ teaspoon cinnamon

Filling:

1. To make the filling attach the paddle attachment to the food processor. Alternatively you can use a hand mixer.
2. Mix the quark and the cream cheese until very fluffy. Continue on the lowest speed and add the sugar, flour, vanilla extract, and salt.400 g cream cheese/ 1 ¾ cups + 250 g quark/ 1 ¼ + 100 g granulated sugar/ ½ cup + 2 teaspoons all-purpose flour + 1 teaspoon vanilla extract + 1 pinch of salt
3. Add eggs: Mix to incorporate, then start adding the eggs and the egg yolk, one by one, mixing well in between. Pour in the heavy cream and combine.2 eggs + 1 egg yolk + 200 ml heavy cream/ scant 1 cup

Assemble and bake:

1. Peel the apples and chop them into small cubes. Mix with lemon juice.2 small apples + 2 tablespoons lemon juice
2. Brush the walls of the springform with some butter. The form is hot so that the butter will melt, and brushing will be very easy.
3. Fill: Place the chopped apples on the base of the cake and carefully pour in the filling. Stir gently to make sure that the apples don't get pushed towards the walls of the springform. Sprinkle the cake with the streusel.
4. Bake for 40 to 50 minutes. The streusel should be pretty brown, and the middle of the cake is still a bit wobbly.
5. Let rest in the oven: Turn off the heat but leave the cake inside the oven. Place a wooden spoon in the oven door to prevent it from closing and leave the cake for another two hours in the oven.
6. Cool: Take it out and let it cool completely. Best served the next day.