Creating the Orange Creamsicle Cake is straightforward if you follow these simple steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Mix Dry Ingredients: In a bowl, whisk together the all-purpose flour, baking powder, and salt.
3. Cream Butter and Sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy.
4. Add Eggs: Add the eggs one at a time, mixing well after each addition. Incorporate the orange zest and vanilla extract.
5. Combine Mixtures: Gradually add the dry ingredients to the butter mixture, alternating with the milk. Mix until just combined.
6. Pour Batter: Divide the cake batter evenly between the prepared pans.
7. Bake: Place the pans in the preheated oven and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool: Remove the cakes from the oven and let them cool in the pans for 10 minutes. Then, transfer them to wire racks to cool completely.
9. Prepare Frosting: In a separate bowl, whip the softened butter until creamy. Gradually add powdered sugar, orange juice, and vanilla extract, mixing until smooth.
10. Frost the Cake: Once the cakes are cool, spread frosting between the layers and on top. Use a spatula to create an even layer.
11. Decorate: Garnish the cake with orange slices and additional orange zest, if desired.

By following these steps, you will create a delicious and visually stunning Orange Creamsicle Cake that everyone will enjoy.