MARBLED CHEESECAKE RECIPES

Steps:

• Whisk together zest, juice, sugar, and eggs in a 2-quart heavy saucepan. Add butter and cook over moderately low heat, whisking frequently, until curd is thick enough to hold marks of whisk and first bubbles appear on surface, about 6 minutes.
• Force lemon curd through a fine-mesh sieve into a wide shallow dish, scraping bottom of sieve, then cover surface with wax paper. Cool completely, stirring occasionally, about 30 minutes.
• Put oven rack in middle position and preheat oven to 350°F. Invert bottom of springform pan (to make it easier to slide cake off bottom), then lock on side. 3Stir together crust ingredients in a bowl, then press onto bottom and 1 inch up side of springform pan. Place springform pan in a shallow baking pan and bake 10 minutes, then cool crust completely in springform pan on a rack.
• Reduce oven temperature to 300°F.
• Beat together cream cheese and sugar in a bowl with an electric mixer at medium speed until smooth, 1 to 2 minutes. Reduce speed to low and add eggs 1 at a time, beating until incorporated. Beat in sour cream and vanilla until combined.
• Pour two thirds of cream cheese filling into crust, then spoon half of lemon curd over filling and swirl curd into filling with a small knife. (Avoid touching crust with knife to prevent crumbs getting into filling.) Repeat with remaining filling and curd.
• Bake cheesecake until set 1 1/2 inches from edge but center trembles when pan is gently shaken, about 45 minutes. (Center of cake will appear very loose but will continue to set as it cools.) Transfer springform pan to a rack and immediately run a knife around top edge of cake to loosen. Cool completely, about 2 hours, then chill, uncovered, at least 4 hours. Remove side of springform pan before serving.

Steps:

• Line the base of a 20cm (8in) round, deep springform tin with a circle of baking parchment.

  To make the base, mix the crushed biscuits with the melted butter and press into the base of the tin. Level using the back of a spoon.

  To make the filling, put the chopped white chocolate in to a bowl and sit over a pan of just hot water. Leave to melt (but don't allow it to get too hot), stirring occasionally, then set aside to cool a little.

  Reserve 3 tablespoons of the double cream. Pour the remainder into a large bowl, then add the cream cheese and vanilla. Whisk, using an electric hand whisk, until smooth. Add the melted white chocolate and whisk again until smooth and thick.

  Spoon about 6 tablespoons of the white chocolate filling into a mixing bowl. Spoon the remaining mixture into the tin and smooth over the top. Chill for 30 minutes.

  Add the reserved double cream to the reserved white chocolate mixture and mix together until smooth. Spoon over the set mixture in the tin.

  Melt the dark chocolate as before and then drizzle over the top of the cheesecake and use the blade of a knife to swirl the toppings together.

  Chill for a minimum of 2 hours, then turn out and cut into wedges to serve.

  To prepare ahead: can be made up to 2 days ahead and kept in the fridge.

  To freeze: once set and chilled this freezes well.