Nectarine cake with orange and lemon recipe

Ingredients

• 1 kilogram ripe nectarines, halved, stoned
• 1 cup (220g) caster sugar, plus 2 tablespoons extra
• 200 grams butter, at room temperature
• 1 lemon, finely grated rind of
• 1 orange, finely grated rind of
• 3 large eggs
• 1 2/3 cup (250g) self-raising flour, sifted
• 1 teaspoon baking powder, sifted
• 2/3 cup (160ml) buttermilk
• thickened cream or vanilla ice-cream (optional), to serve