Lemon Cake with Haupia Filling & Hibiscus Buttercream

INGREDIENTS

2 1/4 cups

cake flour

1 tbsp

baking powder

1/2 tsp

salt

1 1/4 cups

buttermilk, at room temperature

large egg whites, at room temperature1 teaspoon pure vanilla extract

1/2 tsp

pure lemon extract

1 1/2 cups

sugar

lemon zest from two lemons

1/2 cup

unsalted butter, at room temperature

2 tbsp

+ 1 teaspoon cornstarch

1/4 cup

+ 1 1/2 tablespoons water

1 1/2 cups

full-fat coconut milk

1/4 cup

+ 1 tablespoon granulated sugar

1/4 tsp

salt

1 tsp

pure vanilla extract

1/2 tsp

coconut extract or spiced rum (optional)

large egg whites

1 1/4 cups

sugar

1/4 cup

hibiscus simple syrup (see notes)

3 sticks

butter (1 1/2 cups), softened and cut into 1 tbsp pieces

2 tsp

lemon zest