For the hibiscus curd:
4 large eggs
2 egg yolks
1 cup sugar
1/3 cup lemon juice *
1/4 teaspoon salt
20 seeded fresh hibiscus calyxes (or 1/4 cup dried hibiscus) **
1/2 cold stick of butter, cut into pieces (2 ounces, or 1/4 cup)
For the chocolate cake:
Butter for greasing the cake tins
15 ounces cake flour *** (about 4 cups sifted)
1 teaspoon baking powder
3/4 teaspoons baking soda
4 ounces cocoa powder (about 1 cup + 2 T sifted)
6 tablespoons softened unsalted butter, at room temperature (3 ounces)
1/2 cup olive oil (plain, not extra virgin, or use another neutral-flavored oil)
1 2/3 cups sugar
1/4 teaspoon salt
2 large eggs at room temperature
2 large egg yolks at room temperature
1 cup whole milk at room temperature
For the ganache:
9 ounces dark chocolate
1 cup + 3 tablespoons heavy cream
1 pinch of salt
To assemble the cake:
Optional: 10 to 15 hibiscus calyxes
2 layers of chocolate cake, completely cooled (above)
1 batch of hibiscus curd (above)
1 batch of ganache (above)
* If possible, use a reamer, not a squeezer. Most of the lemon’s flavor is in the zest, and squeezing the whole lemon adds too much lemon flavor to the curd, which overshadows the hibiscus. Here, you want acidity with as little lemon flavor as possible.
** I used fresh hibiscus in the photos above, but I’ve also tested the recipe with dried and it works great. In fact, dried hibiscus will give you a much stronger hibiscus flavor than fresh. But using dried won’t get you the same bright pink color; it will be a little more on the purple side. You can find dried hibiscus in the tea section (cut the tea bags open!), in spice shops, at most Asian and some Middle Eastern markets, and at very well-stocked supermarkets.
*** It’s fine to use all purpose flour, but the cake won’t be quite as tender. In either case, be careful not to over-mix once you add the flour to the wet ingredients.
**** If you don’t have a convection oven, you might need to cook the cakes a couple minutes longer.
***** You can use a 9-inch pan or another size. The cook time will be shorter with a wider pan and the finished cake will be shorter and wider (and you might need a touch more ganache, since most of it ends up on top).