Preheat oven to 150°C. fan-forced. Grease and line the base of a 20cm-round spring-form pan.
Combine rolled oats, flour and coconut in a bowl. In a pan, melt butter, golden syrup and brown sugar and cook for 5 minutes until melted and smooth. Stand for 2 minutes. Add butter mixture to coconut mixture and mix well to combine. Press mixture over the base and sides of the prepared pan, leaving a 1cm edge around the top of the pan. Refrigerate.
For the filling, roughly chop the cream cheese and place in a bowl. Add the ricotta. Mix with an electric mixer on medium speed for 4 minutes or until smooth, soft and creamy. Add the sugar and beat for 4 minutes. Add the salt and vanilla and beat. Add the eggs, one at a time, beating for one minute after each addition. Add the sour cream and beat until incorporated .Add the cream and combine.
Pour the cream cheese filling into the pan and smooth the top. Cook for 1 hour 30 minutes or until filling is just set. Turn oven off. Open the oven door and leave ajar with cake in oven for another hour (this will prevent the surface from cracking).
Once cooked and cooled, cover the cheesecake in cling film and refrigerate overnight.
For the sauce, in a small saucepan, melt the butter, sugar and golden syrup on low heat until melted and combined. Add the cream and bring to the boil. Simmer for 2 minutes. Remove from heat. Cool for 20 minutes. Transfer to a bowl. Cover. Refrigerate overnight.
To serve, eiether drizzle the sauce over the cheese cake before slicing or pour over individual cheescake slices before serving.