Preheat your oven to 350°F.

Line the bottom and sides of an 8-inch round pan with parchment paper and set it aside.

In a bowl, use a mixer at low speed to beat the egg whites for 2 to 3 minutes or until soft peaks form.

Gradually add ¼ cup of the granulated sugar, a tablespoon at a time, while continuously beating. Once all the sugar is added, increase the speed to medium and continue beating the meringue until it forms stiff, glossy peaks. Set it aside.

In a separate bowl, cream the butter and the remaining ¼ cup of sugar for about 3 minutes or until it becomes light in color.

Add the egg yolks one at a time while continuously mixing for about 2 minutes.

Add the milk, cake flour, baking powder, and vanilla extract to the egg yolk mixture. Beat the batter for about 2 minutes or until it becomes smooth.

Gently fold in one-third of the meringue into the egg yolk mixture, and then add the remaining meringue, folding until well combined.

Pour the batter into the prepared pan and bake for 30 minutes in the preheated oven or until a toothpick inserted in the center comes out clean.

Remove the cake from the oven and let it cool in the pan for about 10 minutes before completely removing it from the pan onto a cooling rack. Remove the parchment paper from the cake and allow it to cool down before frosting.

In a bowl, combine condensed milk, egg yolks, and salt (if using) and whisk until well-blended and evenly colored.

In a wide, nonstick pan over medium-low heat, melt the butter until it's slightly melted and warm (NOT hot).

Add the egg-milk mixture to the pan and stir well to combine.

Cook the mixture, stirring regularly and scraping the sides and bottom with a spoon, for about 15 to 20 minutes or until it thickens to a spreadable paste. Remove it from heat and allow it to cool.

Once the sponge cake is completely cool, cut it horizontally into half.

Spoon about ¼ of the yema frosting on top of the bottom cake half layer. Using a spatula, spread it evenly to cover the surface with an approximate thickness of ⅛ inch.

Place the top layer half of the sponge cake on top of the frosted cake layer.

Scoop and spread enough yema frosting on top of the cake to cover the surface and create a frosting layer with a thickness of about half a centimeter.

Set aside about ¼ cup of the yema frosting and, using an offset spatula, spread it to cover the sides of the cake.

Pipe the reserved ¼ cup of yema frosting on the top and at the bottom edges of the cake to decorate.

Sprinkle grated cheese on top of the cake.

Serve the cake immediately or chill it in the fridge.