- For lemon butter/curd: Combine lemon juice and butter in a heavy-based saucepan and stir over low heat until butter melts. Whisk sugar, egg yolks and eggs in a bowl until combined, mix in the cornflour and add to lemon juice mixture.
- Stir continuously on very low heat for 4-5 minutes or until mixture thickens slightly, transfer to a container and refrigerate until completely cold.
- For lemon and thyme syrup: Combine the castor sugar, lemon juice and 125 ml water in a small saucepan and stir over medium-high heat until sugar dissolves and bring to the boil. Add the thyme and simmer until it becomes a syrup. Cool completely.
- To make the sponge: Preheat oven to 160°C and line two 24 cm cake tins with baking paper
- Use an electric mixer on high speed and whisk the eggs, sugar and lemon rind for ±7 minutes or until tripled in volume. Sift the flour, and baking powder together then sift it into the beaten egg mixture. Fold through using a large metal spoon, add the melted butter and thyme and fold through gently to combine.
- Pour the batter into the prepared cake tins. Bake for ±25 minutes or until golden and centre springs back when pressed gently with a fingertip. Cool for about 5 minutes in cake tins, then transfer to a wire rack and cool completely.
To assemble the cake: Spread the one cake with the whipped cream and lemon butter and sandwich with the other cake. Drizzle syrup over the cake and top with blueberries and a few sprigs of fresh thyme.
