Baked New York Cheescake

This is taken from Florence's blog again. But I wasn't so successful, my cake sank and cracked thou it still taste nice. I strongly think and confirmed that my oven is the cause of it. (-.-'''). I WANT A NEW OVEN!

Ingredients: (for 20cm springform cake pan)
Base:
100g digestive biscuits (crushed)
50g unsalted butter (melted - 1 minute on HIGH in microwave)

Filling:
500g Cream Cheese
100g Castor Sugar
3 Eggs
65g Whipping cream
50g Valrhona White Chocolate (melted via double boil)
1/2 zest from 1 lemon
1/2 tsp vanilla essence or 1/2 tsp lemon juice

Method:

1. Toss crushed biscuit crumbs into melted butter.
2. Press this biscuit mixture over the bottom of a lined springform pan and leave aside.
3. Cream cheese and sugar together till smooth and add in the eggs one by one beating till smooth and then add the rest of the ingredients and beat well.
4. Pour filling onto cake base and bake over a hot water bath at 150C for 40 minutes.
5. Remove the water bath now and continue to bake cake till cooked. It may take another 20 - 30 minutes. Remove when cooked and chill completely.