Mix the butter and sugar until creamy.
Add the flour and baking powder.
Add the condensed milk.
Press the dough on the bottom and sides of a spring form.
Place in the fridge until the filling is ready.

---

Mix the quark, smetana, cream-cheese (I made it from paneer by kneading it super-fine / See the index to make paneer), condensed milk, lemon zest and vanilla.
Mix the corn starch with the lemon juice.
Add and incorporate well into the filling.
In the end add the cream.
Pour on the top of the crust.
Bake on the lowest level of the oven in 175 C (347 F) for about an hour.

---

Mix some butter, sugar, flour, bran and almond powder.
Bake on a tray in the oven until golden.
You may want to turn and mix it while baking for an even result.

---

Top the cake with jam (I used blueberry-raspberry jam).
Sprinkle the crumbs on the top.
Let it cool completely.
Carefully remove the sides of the spring-form.
Place the cake on a serving plate

Note:
If you use very sweet jam, you might want to add less sugar in the filling.
Replacing quark with thick yogurt would probably work, too.
Replacing Smetana with crème fraiche, sour cream or cream would probably work, too.