the how-to: cake
1 Preheat the oven to 350ºF. Line the bottoms of two 9-inch round cake pans with parchment paper. Grease the pans and parchment paper.

2 In a medium bowl, rub the orange zest into the granulated sugar (this will help release more flavor from the zest!). Add the cake flour, baking powder, and salt and whisk until combined. 3 In a glass measuring cup or small bowl, stir together the orange juice, heavy cream, and vanilla extract.

4 In a large bowl, whisk together the vegetable oil and egg whites. Add the flour mixture and orange juice mixture in two alternating batches, whisking between each addition. 5 Bake for 20 to 25 minutes, until a tester inserted in the middle comes out with moist crumbs. Cool for 10 minutes in the pan, then turn the layers out onto wire racks to cool completely.

the how-to: buttercream & assembly
1 In a medium saucepan (don’t turn on the stove yet!), whisk together the granulated sugar, cornstarch, orange zest, and salt. Add the eggs one at a time, whisking thoroughly between each addition. Slowly pour in the milk, whisking constantly. Turn on the heat to medium and whisk constantly until the mixture starts to bubble. Once bubbling, continue whisking for 1
minute, or until very thick. Remove it from the heat and whisk in the vanilla extract. Scrape the custard into the bowl of your electric mixer and put it in the fridge to cool completely, about 30 minutes.

2 Once cool, beat the custard in your stand mixer using the whisk attachment on medium-high speed for 2 minutes. With the machine running, add the butter a couple of tablespoons at a time. Continue whipping on medium-high speed for about 4 minutes, until very, very fluffy. 3 Using an offset spatula, fill and frost the cake! For this one, I usually fill the middle and frost the top with thick layers and coat the sides with just a very thin layer, naked cake style. Store in an airtight container at room temperature for up to 3 days.