Lemon Cake with Fluffy, Less-Sweet Lemon Frosting

Step 1: Preheat the oven to 180°C / 350°F (160°C fan) for 20 minutes before starting the batter. Place a shelf in the middle of the oven.

Step 2: Grease three 20 cm / 8-inch cake pans with butter, then line them with parchment paper. If possible, use pans without loose bases.

Step 3: Whisk the flour, baking powder and salt together in a large bowl. Set aside.

Step 4: Beat the eggs for 30 seconds on speed 6 in a stand mixer fitted with a whisk attachment, or with a hand beater.

Step 5: With the beater running, pour in the sugar over 45 seconds.

Step 6: Beat for 7 minutes on speed 8, until the mixture is white and tripled in volume.

Step 7: While the eggs are beating, put the butter and milk in a heatproof jug and microwave on high for 2 minutes to melt the butter, or heat them on the stove. Do not let the milk bubble or boil; foam is fine. If you prepare this ahead, cover it and keep it hot while the eggs beat.

Step 8: When the eggs are whipped, scatter one-third of the flour mixture over the surface and beat on speed 1 for 5 seconds. Add half of the remaining flour and mix on speed 1 for 5 seconds. Add the rest of the flour and mix on speed 1 for 5 to 10 seconds, just until incorporated. Stop as soon as you can no longer see flour.

Step 9: Pour the hot milk and butter, vanilla, lemon juice, lemon zest and oil into the now-empty flour bowl. Add about 1 1/2 cups, or roughly 2 ladles, of the egg batter to the milk mixture. Whisk until smooth; the mixture will look foamy.

Step 10: Turn the beater back on to speed 1 and pour the milk mixture into the egg batter over 15 seconds. Turn off the beater.

Step 11: Scrape down the sides and base of the bowl. Beat on speed 1 for 10 seconds, until the batter is smooth and pourable.

Step 12: Pour the batter into the prepared pans.

Step 13: Bang each cake pan on the counter 3 times to knock out large bubbles.

Step 14: Bake for 23 minutes, or until golden and a toothpick inserted into the centre comes out clean.

Step 15: Remove the cakes from the oven and cool them in their pans for 15 minutes. Gently turn them out onto cooling racks. For layer cakes, cool them upside down so any slight dome flattens.

Step 16: Let the cakes cool completely before frosting. Frost with the lemon frosting prepared below.

Step 17: Put the flour and sugar in a large saucepan over medium heat. Cook, stirring constantly, for 30 seconds.

Step 18: Whisk constantly as you slowly pour in the milk to prevent lumps. As the milk heats and the mixture begins to thicken, keep stirring so it does not catch on the base of the pan.

Step 19: Cook until the mixture thickens to a thick, dolloping custard consistency.

Step 20: Remove the pan from the heat and scrape the mixture into a bowl. Cover with plastic wrap, pressing it onto the surface to prevent a skin from forming. Cool completely, about 20 minutes on the counter followed by 30 minutes in the refrigerator. Do not let it become refrigerator-cold; it will firm into a very thick paste.

Step 21: Beat the softened butter with a hand beater or stand mixer fitted with a whisk attachment for 3 minutes, until smooth and very pale yellow, almost white.

Step 22: With the mixer on speed 5, add the roux one heaped tablespoon at a time, taking about 1 minute to add it all. Add the lemon zest and juice, then whip for 2 minutes, until the frosting holds peaks like whipped cream. Do not whip for more than 4 to 5 minutes, or the starch may activate and make the frosting sticky.

Step 23: Turn one cake layer upside down for a level surface. Spread it with a 3 to 4 mm / 0.12 to 0.16-inch layer of frosting. Add another cake layer and spread it with more frosting. Top with the final cake layer, then use the remaining frosting to cover the top and sides.