Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans with butter or cooking spray and coat with a thin layer of flour.

In a mixing bowl, whisk together the all-purpose flour, baking powder, and salt until well blended.

In another large bowl, beat together the softened butter and granulated sugar until light and fluffy, about 3–5 minutes.

Add the eggs one at a time, mixing well after each addition. Add vanilla extract and mix until well combined.

Mix in buttermilk, fresh orange juice, and orange zest until smooth.

Gradually add the dry ingredient mixture to the wet mixture, mixing just until incorporated.

Pour the batter evenly into the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Let the cakes cool in the pans for about 10 minutes, then transfer to wire racks to cool completely.

Make the frosting by beating together softened butter, powdered sugar, and orange zest until smooth. If using cream cheese, add it now.

Once the cakes are cooled, frost one layer with orange frosting, place the second layer on top, and frost the sides and top of the cake.

Garnish with additional orange zest or candied orange slices before serving.