Ambrosia Cake

Preparation

1. Step 1

   Bake the cake: Heat oven to 350 degrees and place a rack in the middle. Butter two 9-inch cake pans and line with parchment paper on the bottom.

2. Step 2

   In a medium bowl, whisk together flour, baking powder and salt. In a separate bowl, whisk together milk, coconut milk, rum and vanilla.

3. Step 3

   In the bowl of an electric mixer, beat butter, coconut oil and sugar together until light and fluffy, about 3 minutes. Beat in egg yolks, one at a time, then beat in zest. Beat in half the flour mixture, followed by half the milk mixture. Repeat, beating just until combined and scraping down bowl as necessary.

4. Step 4

   In a separate bowl, use an electric beater to whisk egg whites just until stiff peaks form. Fold into cake batter.

5. Step 5

   Divide batter between pans. Bake until lightly golden and toothpick inserted in center comes out clean, about 30 minutes. Transfer pans to a wire rack to cool for 10 minutes, then unmold cakes and cool completely on rack. (Cakes can be made up to 2 days ahead; once cool, wrap in plastic and refrigerate.)

6. Step 6

   Meanwhile, make the filling: Bring clementine juice and lemon juice to a boil over medium heat in a medium saucepan. In a medium bowl, whisk together eggs, yolks, sugar and salt. Whisking constantly, slowly pour hot juice into eggs, then return mixture to saucepan. Cook over medium heat, stirring constantly, until thickened, about 5 minutes. Remove from heat; whisk in butter and vanilla. Push through a strainer set over a medium bowl, and stir in clementine zest. Cover with plastic wrap directly on surface of curd and refrigerate until cold. (Curd can be made up to 5 days ahead.) Or to speed up cooling, set bowl of curd in a larger bowl filled with ice water and stir curd until very cold, 7 to 10 minutes. Cover and refrigerate until needed.

7. Step 7

   Prepare clementines for decorating the cake: Cut the top and bottom off a clementine and set it cut-side down on a cutting board. Use a sharp knife to cut away peel and pith, following the curve of the fruit from top to bottom. Working over a bowl to catch the juices, carefully cut out each segment from the membrane; it should fall into the bowl as you cut. Lay segments out on paper towels to dry slightly while you cut remaining fruit.

8. Step 8

   Use a large knife to trim tops of cakes to level them, and cut both cakes in half horizontally to make layers.

9. Step 9

   Place a cake layer on a serving dish and spread a third of the curd over it, leaving a 1-inch border around the edge. Layer a third of the clementine segments on top of curd, spacing them evenly so cake will be balanced. Top with another layer, spread another third of curd over it, and layer with ½ cup shredded coconut. Top with cake layer, repeat curd and clementines, saving some clementines for top of cake. Place the remaining cake layer on top, and chill while making frosting.

10. Step 10

    Make the frosting: Bring a medium pot with 1 inch of water to boil. In the bowl of an electric mixer, combine egg whites, sugar, cream of tartar and salt. Set bowl over simmering water and whisk constantly until eggs reach 160 degrees, or the sugar has melted. Remove from heat, and beat on medium-high speed until stiff peaks form, about 5 minutes.

11. Step 11

    Immediately spread frosting on cake and press coconut shreds into tops and sides. Top with clementine wedges and strawberries if using; serve within an hour or two. (Or, keep refrigerated for up to 8 hours and wait until just before serving to top with fresh fruit.)