1 Prep the oven and pan: Preheat the oven to 350°F. Grease a 9×13 inch baking pan.
2 Combine the dry ingredients: Sift the flour, cocoa, baking powder, soda, and salt into a large mixing bowl.
3 Make the batter: In a measuring cup combine the boiling water, chocolate, and espresso. Cover and let the hot water melt the chocolate, about 10 minutes, and whisk until smooth. Check the water with your finger; it’s fine if it’s still a little warm, but it should no longer be hot to the touch.
In a separate bowl (or in your measuring cup, if it’s large enough), combine chocolate-water with the sugar, eggs, oil, and vanilla extract. Whisk to combine.
Pour the chocolate mixture into the flour mixture and beat, using a stand mixer or a hand mixer, until just combined. Stop periodically and scrape the bottom of the bowl.
4 Bake the cake: Spread the batter into the pan and bake for 25 to 35 minutes or until the top springs back to the touch, the sides of the cake have pulled slightly away from the pan, and a toothpick inserted into the center comes out clean.
Leave the cake in the pan, and set it on a wire rack to cool completely before frosting, about 45 minutes.
5 Make the frosting: Whisk together the egg yolks, evaporated milk, and brown sugar in a saucepan. Add the butter and warm over medium-high heat, stirring constantly until the mixture thickens, about 10 minutes. Remove from the heat and stir in the vanilla and salt, followed by the coconut and pecans.
The frosting should be thick, creamy, and nubbly with coconut and pecans.
6 Finish the cake: Cool the frosting to room temperature and spread generously onto the cake. Serve the cake from the pan.
The cake can be made a few days ahead, but wait to top it with the coconut-pecan frosting until before serving. This cake is best served the same day it’s frosted. Leftovers can be kept, covered, for 2 to 3 days at room temperature.