In a saucepan that a bowl can sit on top of or double broiler, pour about 2 inches of water and bring it to a simmer. (The bowl should be able to sit on top without touching the water)

In a bowl, add lemon juice, eggs, egg yolks, sugar, and salt. Place the bowl on the saucepan and whisk the curd continually until the mixture becomes very think, this will take about 10-12 minutes (or it is 180° F on a thermometer.)

Remove the bowl from the saucepan and cool until it reaches 140° F, stirring from time to time to release the heat.

While it is cooling, cut butter into 1-tablespoon cubes. When the curd is ready, whisk in the butter 1 tablespoon at a time, stirring until melted after each piece.

Once all the butter is added, the curd will be pale yellow and thick.

Pour into a bowl and press a piece of plastic wrap on top to prevent the curd from forming a skin. Set in the fridge for 3-4 hours or overnight until set before using in the cake.

Preheat the oven to 350 F.

Sift together the flour, ⅓ cup of the sugar, salt, and baking powder into a medium bowl.

Add in the egg, water, and oil and mix until no lumps remain.

In a second bowl with a hand mixture or in the base of a stand mixer, mix the egg whites with the cream of tartar

With the mixer on low speed, slowly pour in the remaining ¼ cup of sugar. Whip the egg whites and sugar together until a meringue forms.

Fold the batter together with the meringue and pour into an ungreased 9 inch cake pan. Do not line or grease the cake pan or it will fall out when it cools. Bake for 30-40 minutes or until a toothpick comes out clean. It will be golden brown on top

After baking, invert the cake onto a cooling rack to cool

Prepare the whipped cream by whipping together the whipped cream, vanilla bean paste, and sugar until medium peaks form

Take 1/3 cup of the lemon meringue and reserve for topping.

Take the remaining lemon meringue and divide it in half (After this step, there will be 3 bowls in total - 1/3 cup for topping and two even bowls for filling)

Take 1 cup of the whipped cream and fold it into one of the filling lemon curd bowls.

Cut the cooled cake in 4 even layers. We like to do this by cutting it in half and then each in half again. They will be thin.

Once all the layers are filled, set in the fridge for 1 hour to set

Once set, top with the remaining whipped cream and remaining 1/3 cup of lemon curd (we like to swirl this into the whipped cream on top)