- Preheat oven to 170°C. Grease and line the base of a 20cm round cake tin.
- For the Ginger Fluff, place sugar and lemon zest into the bowl of a stand mixer and whisk for 2 minutes to combine.
- Add eggs and whisk until white and fluffy and almost tripled in volume, approximately 8-10 minutes.
- Warm the butter and golden syrup together in the microwave or in a saucepan until the butter is just melted, but not too hot. Set aside.
- Meanwhile, sift the remaining dry ingredients into a separate bowl. Add a pinch of salt and lightly whisk to combine.
- Gently fold into the egg mixture, taking care to not knock out all of the air from the egg mixture, until almost combined.
- Slowly pour the butter mixture around the edge of egg mixture and gently fold through until fully incorporated.
- Slowly pour batter into the prepared tin and bake for 25-30 minutes. The top of the cake should bounce back in the middle when pressed with your finger and mixture will pull away from the edge of the tin when done. Cool in the tin for 10 minutes, then invert onto a wire rack lined with baking paper to cool completely.
- Once completely cool, slice horizontally through the centre of the cake to ice.
- For the Custard Buttercream, prepare the custard base. Combine the ½ cup sugar and fine lemon zest in the bowl of a stand mixer fitted with a paddle attachment. Add the egg yolks, cornflour, flour and salt and immediately beat together until creamy and pale.
- Meanwhile, place milk, cream and ginger into a medium saucepan over medium heat and bring to just below boiling point. Remove the saucepan from the heat and carefully pour 1/3 of the hot milk mixture into the yolk mixture, whisking continuously to keep the eggs from scrambling. Once incorporated add another 1/3 of the mixture, whisk well and finally add the last 1/3 of the mixture.
- Return the mixture to the saucepan. Place over low heat, whisking continuously, until the mixture thickens. Remove the pan immediately from the heat when bubbles appear and whisk for another minute to cool the custard slightly.
- Pour the custard into a clean bowl and cover the surface with cling film. Place into the fridge to cool completely.
- Place a small saucepan over medium-high heat. Add the remaining ¼ cup sugar, water and lemon strips and stir well until sugar has dissolved. Bring to a boil then reduce the heat and simmer until syrup thickens slightly, approximately 3-5 minutes. Remove from heat and allow to cool. Once cool, remove the lemon zest strips for garnish and reserve the syrup for the buttercream.
- Once the custard is cooled, beat the butter and vanilla bean paste in a medium-sized bowl until smooth and very fluffy, approximately 3-5 minutes. Add the cold custard, one tablespoon at a time, mixing well after each addition. Once all the custard has been added, mix for another few minutes, until the buttercream looks thick, smooth and creamy.
- Add some reserved lemon syrup and salt, to taste and mix until incorporated.
- Transfer mixture to a piping bag fitted with a large star piping tip.
- To assemble, place the bottom half of the cake onto a serving platter. Pipe half the Custard Buttercream over the surface. Carefully cover with the top half of the cake. Pipe rosettes on top of the cake with the remaining custard buttercream. Dust the cake top and edges with icing sugar. Place the gooseberries evenly around the top of the rosettes, alternating with the fresh edible flowers. Finally, sprinkle the candied lemon strips over the top of the remaining buttercream rosettes and serve.