In a medium saucepan, combine 1 cup of sugar, 1/4 cup of cornstarch, and a pinch of salt. Gradually stir in 1 cup of freshly squeezed orange juice, then cook over medium heat until the mixture thickens, about 5-7 minutes. Remove from heat and whisk in 4 egg yolks, returning it to the stove until it reaches a gentle simmer. Stir in 1/4 cup of unsalted butter and 1 tablespoon of grated orange zest until melted and smooth. Transfer to a bowl, cover with plastic wrap, and refrigerate to cool.

Preheat your oven to 350°F (175°C). While the oven heats, grease and flour two 9-inch round cake pans to prevent sticking. In a large mixing bowl, cream together 1/2 cup of unsalted butter and 1 1/2 cups of sugar until light and fluffy, about 3-5 minutes. Add in 4 egg whites, mixing until well incorporated, then blend in 1 teaspoon of clear vanilla extract and the zest from 1 orange.

In a separate bowl, whisk together 2 cups of cake flour and 2 teaspoons of baking powder, then slowly add this dry mixture into the creamed butter and sugar. Mix until just combined. Gradually add 1 cup of 2% milk, mixing until the batter is smooth and well-blended. Pour the cake batter evenly into the prepared pans, smoothing the tops for even baking.

Place the pans in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Keep an eye on them; the edges should be lightly golden, and the center should spring back when gently pressed. Once baked, cool the cakes in the pans for 10 minutes, then transfer them to wire racks to cool completely.

In a heatproof bowl, combine 4 egg whites and 1 cup of sugar. Set this bowl over a pot of simmering water, whisking continuously until the mixture reaches 160°F (70°C) to pasteurize the eggs, which takes about 5 minutes. Once heated, beat the mixture until it forms stiff peaks and is cool to the touch, about 10 minutes. Gradually add in 1 cup of softened unsalted butter and 4 ounces of melted white baking chocolate, beating until smooth and creamy.

Place one cake layer on a serving plate. Spread a generous layer of the cooled orange curd on top, then carefully place the second cake layer on top of the curd. Use the buttercream to frost the top and sides of the entire cake, smoothing it out for a clean finish.

To create the adorable bunny features, use assorted candies and fluffy decorations. Attach skewers for added stability if necessary while placing the candy to form eyes, nose, and whiskers. Finally, dust the top of the cake with coarse sugar for sparkle and texture.