Orange Cake with Pastel Gradient Buttercream

I have a great orange cake recipe to share with you today, using a method that's very different from cakes I've done before but isn't too much of a hassle; and it makes a great, moist cake!  I topped mine off with orange flavoured buttercream for a coworker's birthday.

Recipe adapted from: Sweetapolita
Ingredients - cake (20cm (8 inch) round cake)
345g flour
400g white sugar
19g baking powder (1 tbsp + 1 tsp)
1/2 tsp salt
4 whole eggs
2 egg yolks
240mL milk
60mL orange juice
170g cold butter
Zest from 2 oranges

Ingredients - orange buttercream
454g butter (room temperature is best)
565g icing sugar
60mL strained orange juice

Method - cake
1. Preheat the oven to 175 C (350 F).  I did this in a two layer cake, so I buttered and lined two 22cm round tins, but you can use three for a three layer cake if you like!

2. Whisk the flour, sugar, baking powder and salt in an electric mixer with the paddle attachment.

3. Chop the butter into rough cubes.  With the mixer on a slow speed, add the cubes one at a time, waiting a few seconds in between.

4. Once all the butter is added, keep mixing until the mixture is crumbly and all the butter is combined.

5. Mix the milk and orange juice together, then gradually add it to the flour mixture and mix until combined.

6. Mix the whole eggs and the egg yolks with a fork, then add them gradually to the batter and beat until combined.

7. Finally, add the orange zest and mix gently.

8. Portion the batter evenly between your cake tins and bake for about 30 minutes (if you're using two cake tins), or until an inserted toothpick comes out with just a few crumbs.

9. Let the cakes cool in the tin then turn them out onto wire racks.

Method - orange buttercream
1. Beat the butter until smooth and creamy.  I use the paddle attachment on my mixer.

2. Add the icing sugar and orange juice, and beat until the icing is light and fluffy.  This will take a few minutes.

3. If desired, tint the icing with food colouring.  For this cake, I left some buttercream un-coloured and tinted some a pale peachy orange.

Assemble the cake by sandwiching the cake layers with buttercream, then fully icing the outside of the finished cake.

I made an attempt at Sweetapolita's beautiful swirly gradient decoration (video tutorial here) with my peach coloured and white buttercream, and I feel pretty good about how it turned out!  I gave the top of the cake an extra bit of colour by swiping some of the peach coloured buttercream around the outside in a circle, then finishing off with some orange sprinkles.