120 gm soft butter 240 gmgolden caster sugar2eggs125 ml (½ cup) buttermilk225 gm plain flour75 gmground hazelnuts1 tsp eachbaking powder and bi-carbonate of soda20 gmcoarsely chopped hazelnutsTo serve:crème fraîche or mascarpone (optional) Ricotta filling150 gm ricotta1egg yolk25 gmgolden caster sugar1vanilla bean, scraped seeds only150 gmmixed berries, such as strawberries, raspberries and blackberries 30 gmgolden caster sugar1 tbsplemon juice
Preheat oven to 160C. Beat 110gm butter and 220gm sugar using an electric mixer until pale and fluffy, add eggs and beat until smooth and combined, add buttermilk and beat to combine. Add flour, ground hazelnuts, baking powder and bi-carbonate of soda and beat to combine. Spoon half the mixture into the base of a greased and floured 18cm-diameter cake pan and set aside.
For ricotta filling, process ingredients in a food processor until smooth, then spread over cake mix in pan.
For berry filling, combine berries (cut strawberries, if using, into quarters), sugar and lemon juice in a bowl, then spoon over ricotta filling.
Spoon remaining cake mixture over berries and smooth top. Combine remaining butter and sugar in a small bowl with hazelnuts and rub together with fingers, scatter over top of cake and bake for 1 hour or until golden and centre is firm to touch when pressed gently with fingertips. Turn off oven and cool in oven. Serve with crème fraîche or mascarpone if desired.