Step 1

Preheat oven to 180°C or 160°C fan. Grease a 22cm springform cake pan. Line base and sides with baking paper, extending 5cm above rim.

Step 2

Place butter, sugar, eggs and vanilla in a food processor and process until smooth. Transfer to a bowl. Add flour, bicarbonate of soda and half of cinnamon, and stir until combined. Gently fold in rhubarb, sour cream and lemon rind. Spoon into prepared pan and smooth surface.

Step 3

Combine extra sugar and remaining cinnamon. Sprinkle over cake. Bake, covering top of cake loosely with foil if topping starts to burn, for 1 hr 10 mins, until a skewer inserted comes out clean. Stand cake in pan for 5 mins. Transfer to a wire rack to cool slightly. Serve with cream.