Preheat oven to 350°F (175°C). Grease and line three 8-inch round cake pans with parchment paper.

In a large bowl, rub the fresh orange zest into the granulated sugar with your fingers until fragrant. Add softened butter and beat for 4-5 minutes until light and fluffy.

Add eggs one at a time, mixing well after each addition. Mix in the vanilla bean paste.

In a separate bowl, whisk together cake flour, baking powder, baking soda, and salt. Combine buttermilk and orange juice in a measuring cup.

Alternate adding the dry and wet ingredients to the butter mixture, beginning and ending with the dry ingredients. Mix just until combined.

Divide batter evenly among pans. Bake for 25-30 minutes until a toothpick inserted comes out clean. Cool completely on wire racks.

Make the frosting: Beat softened butter for 5 minutes until pale. Gradually add powdered sugar, mixing on low. Add orange juice, orange extract, and vanilla bean paste. Whip on medium-high until fluffy.

Assemble the cake: Layer the cooled cakes with frosting. Apply a thick layer of frosting to the outside. Use an icing comb to create horizontal ridges on the sides and pipe a decorative border along the top and bottom.