Step 1

Begin by preheating the oven to 325 degrees Fahrenheit or 165 degrees Celsius.

Step 2

Line three 8-inch pans with parchment rounds and spray with non-stick baking spray.

Step 3

Add 1 cup unsalted butter and 2 1/2 cups of sugar into the bowl of a stand mixer and mix on high for 1 minute with a whisk attachment or a hand mixer. The mixture should become light in color.

Step 4

Add in 4 large eggs, two at a time. Mix on medium high until they're fully incorporated.

Step 5

In a separate bowl, combine the 1 cup orange juice, 1 cup of buttermilk, 1 cup of black cocoa, 2 Tbsp of fresh orange zest, and 2 tsp orange emulsion or extract. Whisk until no clumps remain.

Step 6

Next, mix 1 cup of self-rising cake flour into the butter/egg mixture on a low speed. Scrape the sides of the bowl with a rubber spatula to make sure the flour gets fully mixed in.

Step 7

Pour in half of the orange juice/cocoa mixture and gently pulse the mixture at first to incorporate the liquid (if you don't, you'll end up splattering the cocoa mixture all over you kitchen!). Then mix on low until incorporated.

Step 8

Repeat with another cup of cake flour followed by the remaining orange juice/cocoa mixture, scraping the sides of the bowl as needed.

Step 9

Add in the 3rd cup of self-rising cake flour and mix on low until the flour is just incorporated. Scrape the sides as needed. You want to be careful not to overmix the batter or else you'll end up with dense cake layers!

Step 10

Pour the batter evenly between the prepared cake pans. I like to use a kitchen scale to ensure each pan has exactly the same amount of batter.

Step 11

Bake for 32-35 minutes, or until a toothpick comes out clean.

Step 12

Allow the layers to cool in the pans for about 10 minutes, then run an offset spatula around the edge of the pans to help separate the layers from the pans.

Step 13

Once the layers are fully cooled, carefully flip the pans and remove the layers from the pans.

Step 14

Use a serrated knife to level the tops of the layers, then set aside.

Step 15

While the cake layers bake and cool, make the chocolate orange buttercream frosting.

Step 16

Beat 1 1/2 cups of unsalted butter on a medium speed for 30 seconds with a paddle or whisk attachment until smooth.

Step 17

Mix in 1 tsp orange emulsion or extract, 2 Tbsp fresh orange zest and 1/2 tsp salt on a low speed.

Step 18

Slowly add in 3 cup powdered sugar on at a time.

Step 19

Scrape the sides and bottom of the bowl as need with a rubber spatula.

Step 20

Add 1/2 cup of heavy cream half through adding in the powdered sugar to make it easier to mix.

Step 21

Mix in 1 cup dark cocoa powder on a low speed.

Step 22

Pour in 2 cups of cooled, melted chocolate.

Step 23

Beat on low until the ingredients are fully incorporated and the desired consistency is reached.

Step 24

If the frosting is too thick, add an extra Tbsp of heavy cream. If it's too thin, add in another 1/4 cup of powdered sugar. Repeat until the frosting is the right consistency.

Step 25

Stir by hand with a rubber spatula to get the frosting SUPER smooth. Cover with plastic wrap and set aside.

Step 26

If possible, chill your cake layers in the freezer for 20 minutes before assembling the cake. It makes them cold to the touch, which minimizes crumbing and makes them so much easier to frost and stack them.

Step 27

Spread about 1 Tbsp of orange chocolate frosting onto a greaseproof cake board or plate, then place your first cake layer on top of frosting smear. This helps the layer stay in place as you assemble the cake.

Step 28

Spread 1/4 cup of orange marmalade directly onto the cake layer, being careful not pull up too many crumbs.

Step 29

Spread an even layer of orange chocolate frosting on top of marmalade with a large offset spatula.

Step 30

Repeat with the remaining cake layers, being sure to flip the top cake layer upside down (cut side down). This makes it easier to get sharp edges on your cake!

Step 31

Cover the cake in a thin coat of chocolate orange frosting. Smooth using a bench scraper, then chill the cake in the fridge (10 minutes) or freezer (5 minutes) until the frosting is firm to the touch.

Step 32

Add a second, thicker layer of orange chocolate frosting to the cake, and smooth using a bench scraper or icing comb. I chose to use an icing comb to give the sides of the cake a bit of texture.

Step 33

Decorate as desired! I chose add a partial chocolate ganache drip, and used some candied orange slices, orange spirals, and orange zest to decorate the top of the cake.