Cream together 3 tablespoons of unsalted butter and 1 cup of powdered sugar until smooth. Mix in 1 egg white and 2 tablespoons of cake flour.

Line a sheet pan with parchment paper and dollop colored paste onto the pan, creating a marbled effect. Refrigerate for 30 minutes.

Preheat your oven to 450°F (232°C). Whisk together 1 cup of cake flour and 2 tablespoons of cornstarch.

Beat 4 egg yolks, 2 whole eggs, and 1 cup of granulated sugar until pale and thick, about 4-5 minutes.

Fold the flour mixture into the egg mixture, then fold in beaten egg whites until combined.

Spread the cake batter over the chilled color paste and bake for approximately 7 minutes.

Invert the cake onto a dusted kitchen towel, peel off parchment, and roll it while still hot. Let cool for 30 minutes.

Whip 1 cup of heavy whipping cream with 2 tablespoons of powdered sugar and 1 teaspoon of vanilla until stiff peaks form, about 3-5 minutes.

Unroll the cooled cake, spread whipped cream filling, then roll back tightly. Wrap in plastic wrap and refrigerate for at least 1 hour before serving.