The Best Lemon Roll Cake

Lemon curd:

1. Wash and dry the lemon. Zest them first, then halve them and juice them.
2. Place the diced butter, sugar, salt, lemon zest, and juice into a heatproof bowl.
3. Bring a pan of water to a gentle simmer. Place the bowl on top; its bottom should not touch the water.
4. Heat the ingredients, stirring often, until the sugar dissolves.
5. Eggs: In the meantime, beat the eggs and strain them into another small bowl.
6. Add them to the sugar mixture and stir continuously until it thickens slightly and becomes opaque. You should be able to trace a path with your finger on the curd on the spoon (See picture in the blog post).
7. Transfer the curd to a clean bowl, place a piece of clingfilm directly onto the surface of the curd and let cool completely.

Sponge:

1. Preheat the oven to 200°C/ 400°F. Line a baking tray with baking paper.
2. Egg whites: Separate the eggs. Beat the egg whites with a pinch of salt until quite stiff. Gradually add 2 tablespoons of the granulated sugar and beat until glossy and stiff. Set aside.
3. Egg yolks: In another bowl, whisk the egg yolks and 2 tablespoons of sugar until foamy.
4. Combine: Mix the flour, baking powder, and the cornstarch and sieve everything over the egg yolk-sugar mixture. Add ⅓ of the egg whites and incorporate. Add the remaining egg whites and fold in gently.
5. Bake: Spread the batter onto the prepared baking tray and bake for 8 to 10 minutes until golden.
6. Roll sponge: In the meantime, place a clean kitchen towel on the table and sprinkle it with the icing sugar. Turn the baked cake onto the kitchen towel with the baking paper facing up. Peel off the parchment paper carefully, then immediately roll the cake with the help of the towel. Leave it to get completely cool (it will take about 1 hour).

Assemble the roll cake:

1. Unroll the cake.
2. Spread the lemon curd evenly on it.
3. Roll the cake again. Wrap in plastic foil/cling film and place on a platter.
4. Refrigerate for 2 to 4 hours or until nicely set. Remove the plastic wrap and place the cake back onto the serving platter.
5. Dust with icing sugar and decorate with lemon slices (if desired).