Preheat your oven to 350°F (175°C) and prepare three 8-inch round cake pans by greasing and flouring them.

In a medium bowl, whisk together all-purpose flour, baking powder, baking soda, and salt until well combined.

In a large mixing bowl, beat the softened unsalted butter and granulated sugar together using an electric mixer on medium speed for 3-5 minutes until light and fluffy.

Add the eggs one at a time, ensuring each is fully incorporated before adding the next, then blend in the fresh orange zest, juice, and vanilla extract.

Gradually add the dry mixture to your creamed butter mixture, alternating it with the buttermilk until just combined.

Divide the cake batter among the prepared pans and bake for 22-25 minutes until a toothpick inserted comes out clean.

While the cakes bake, make the cranberry filling by cooking fresh cranberries, sugar, orange juice, and zest over medium heat until thickened, then let cool.

For the Citrus Buttercream, beat softened butter, gradually add powdered sugar, then incorporate additional orange juice and zest until light and fluffy.

Once the cake layers are cool, assemble by spreading a layer of buttercream and cranberry filling between each layer and frosting the entire cake with remaining buttercream.