01 -
Preheat the oven to 350°F and position the oven rack in the middle. Spray two or three 9-inch round cake pans with nonstick cooking spray with flour, line bottoms with parchment, and respray.
02 -
Place chopped chocolate in a medium heatproof bowl. Boil the water and pour it over the chocolate. Let stand for 1 minute, then stir until smooth.
03 -
Beat egg whites on high speed with an electric mixer until stiff peaks form, about 1 to 2 minutes. Set aside and clean the beaters.
04 -
Whisk together flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
05 -
In a large bowl, beat butter and granulated sugar until light and fluffy, about 3 minutes. Add egg yolks one at a time, beating after each. Blend in melted chocolate and vanilla extract.
06 -
On low speed, alternate adding dry ingredients and buttermilk in three additions, beginning and ending with dry ingredients. Gently fold in whipped egg whites until batter is uniform.
07 -
Divide batter evenly into prepared pans. Bake for 25-30 minutes if using three layers or 35-40 minutes for two layers, until a toothpick inserted in center comes out clean. Cool in pans 15 minutes, then transfer to wire racks to cool completely.
08 -
Whisk egg yolks, evaporated milk, and brown sugar in a saucepan. Add butter and heat over medium-low, whisking frequently until thickened, about 12 minutes. Remove from heat and stir in coconut, pecans, vanilla extract, and salt. Cool to room temperature.
09 -
Heat heavy cream and corn syrup until boiling. Pour over chopped chocolate; let stand 30 seconds then whisk until smooth. Cool until pourable, whisking occasionally.
10 -
Place one cake layer on a serving platter and spread with coconut-pecan frosting. Repeat for remaining layers, dividing frosting equally if three layers. Drizzle chocolate glaze over the top, allowing it to drip down sides. Slice and serve.