Golden Raisin Ricotta Cheesecake

Crust:
5oz graham crumbs
5 tbs butter, melted
1 1/2 cups golden raisins
1/3 cup Demerara rum
3/4 cup water
Filling:
4 large eggs, separated
1/2 cup plus 2 tbs sugar
1 kg ricotta
1/2 cup sour cream
5 tbs flour
zest of 1 orange
zest of 1 lemon
1/2 tsp vanilla extract
Line bottom of a 9-inch springform pan with parchment paper. In Combine melted butter and graham crumbs. Press into springform. Bake at 350F for 8 minutes.
Bring raisins, rum and water to a boil. Reduce heat, then simmer until liquid evaporates. Arrange over crust.
In a large bowl, using an electric mixer, whisk together egg yolks and 1/2 cup of the sugar until pale in colour; 2 minutes. Beat in ricotta, sour cream, flour, citrus zests and vanilla.
In a separate large bowl, beat egg whites until soft peaks form. Add remaining sugar, beating until glossy. Fold into batter in two additions. Spread batter over top of raisins. Bake 50 minutes or longer, until a tester inserted in centre comes out clean. Let cool on a wire rack for 15 minutes, then run a sharp knife around the edge to prevent cracking. Refrigerate at least 6 hours or overnight before slicing with a hot, dry knife.