summer berry sernik (polish cheese cake)

I can never resist a proper Polish style baked cheese cake. This is a fairly light, and not at all overly sweet version. Theres no biscuit base and it's relatively low in fat and easy to make your own variations. I like this recipe so much that we served it at my recent wedding as part of the afternoon tea offering. It's based on this lovely recipe from the Whiteplate blog.

Ingredients
1kg polish cottage cheese (I use this one)
6 large eggs
190g caster sugar
1 tsp vanilla extract
1/4 tsp salt
1 heaped tbsp cornstarch/cornflour
zest of a lemon
around 300g berries (blackberries, strawberries or raspberries would be my preference but whatever you fancy)

1. Preheat oven to 180C and line a springform cake tin with baking parchment.
2. Beat the cottage cheese with electric whisk until it starts to come together.
3. Add the eggs one at a time beating between each addition.
4. Finally add the salt, vanilla and lemon zest and beat well. You're not trying to beat air into it, just make sure it is smooth and thoroughly combined.
5. Pour into the cake tin, place the berries on top then bake in the oven for 45-60 mins. The centre will still be a bit loose when done but not liquid. Turn off the oven and leave to cool completely with the door left slightly ajar. 
6. Chill for several hours, preferably overnight.