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 orange juice, then cook over medium heat until thickened, about 5-7 minutes. Remove from heat, whisk in 4 egg yolks, return to the stove until gently simmering. Stir in 1/4 cup of unsalted butter and 1 tablespoon of 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). Grease and flour two 9-inch round cake pans. 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, mix well, then blend in 1 teaspoon of clear vanilla extract and 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 smooth and well-blended. Pour into prepared pans, smoothing the tops.

Place the pans in the preheated oven and bake for 30-35 minutes, or until a toothpick comes out clean. Cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

In a heatproof bowl, combine 4 egg whites and 1 cup of sugar. Set over simmering water, whisk continuously until it reaches 160°F (70°C) for about 5 minutes. Beat until stiff peaks form and cool to the touch, about 10 minutes. Gradually add in 1 cup of softened unsalted butter and 4 ounces of melted white chocolate, beating until smooth.

Place one cake layer on a serving plate. Spread a generous layer of cooled orange curd on top, then place the second layer on top. Frost the top and sides of the cake with buttercream for a clean finish.

Use assorted candies and fluffy decorations to create bunny features. Attach skewers for stability if necessary. Dust the top with coarse sugar for sparkle and texture.