4 large eggs + 3 egg whites, room temperature, divided
1½ teaspoons vanilla extract, divided
1½ cups plain flour
2 teaspoons baking powder
½ teaspoon salt
2 tablespoons whole milk
Directions
Preheat the oven to 350 F and line a cupcake tray with 12 cupcake liners.
Zest and juice the four lemons, and then place to one side.
In a large bowl or stand mixer, beat together 1 cup of granulated sugar with ½ cup softened unsalted butter until it is creamed. This should take 3 to 4 minutes.
Then, beat in 2 large eggs and 1 teaspoon of vanilla extract.
In a separate bowl, sift together the flour with the baking powder and the salt. Add this to the bowl containing the sugar, butter, and eggs, and mix until just combined.
Carefully fold in ⅓ cup of fresh lemon juice, 2 tablespoons of lemon zest, and the whole milk, to create a smooth batter.
Transfer the batter to the prepared cupcake cases, filling each one amount ⅔ full, then bake the cupcakes for 20 minutes, until risen and springy. Remove from the oven and set aside to cool.
To make the lemon curd, add 2 large eggs to a bowl set over a saucepan of boiling water. Whisk the eggs thoroughly and then add 2 tablespoons lemon zest and the remaining lemon juice, and ⅔ cup of sugar, and then whisk continually for 7 to 8 minutes, until the mixture coats the back of a spoon. At this point, remove the bowl from the heat and immediately whisk in ½ cup of cubed unsalted butter, until the mixture is thick and glossy. Set to one side to cool.
To make the meringue topping, add the three egg whites to a large clean bowl or stand mixer, and cream of tartar, if using. Beat the egg whites until they are foamy, and then slowly add ¾ cup of granulated sugar to the bowl, one tablespoon at a time, leaving roughly 30 second increments between each addition. The meringue frosting will be ready when it forms stiff peaks, and no longer feels grainy when rubbed between your finger and thumb. Once the meringue topping reaches this stage, mix in the remaining vanilla extract and then transfer it to a piping bag.
To assemble the cupcakes, first cut a small hole in the top of each cupcake, about an inch wide, and scoop out some of the inside of the cupcake. Add a tablespoon of the cooled lemon curd to the hole, and top with the reserved cupcake top. Repeat this for all of the cupcakes.
Pipe swirls of meringue on top of each of the cupcakes, and then place them under a preheated grill for a minute or two, to give them a lovely browned top. Alternatively, you can brown the meringue topping using a handheld kitchen blowtorch.