Preheat the oven to 350°F and grease two 6-inch round cake pans.

Grind the black sesame seeds into a fine powder and mix with the flour and baking powder in a bowl.

Beat 1/4 cup sugar with 4 tablespoons butter until light, then add the egg yolks one at a time.

Alternate adding the dry mixture and milk to the butter mixture until a smooth batter forms. Divide between the pans and bake for 20 minutes until a toothpick comes out clean. Cool the layers completely.

Combine the remaining 1/2 cup sugar, yuzu juice, 2 tablespoons butter, and salt in a small saucepan. Cook over medium heat while whisking in the egg whites until the mixture thickens into a curd. Remove from heat and let cool.

Whip the remaining 2 egg whites with the leftover 2 tablespoons butter until soft peaks form, then spread over the assembled cake. Use a kitchen torch to toast the meringue lightly.

Finish with the toasted black sesame seeds scattered on top.