For the Chantilly Frosting

1. Melt the butter in a medium saucepan over medium—low heat.
2. Remove from heat and add evaporated milk, vanilla and sugar, whisk until combined.
3. Sift cornstarch in mixture and whisk thoroughly until there are no lumps. 
4. Add eggs and egg yolks one at a time, whisking between each addition.
5. Return to stovetop and cook over medium heat until it boils.  
6. After it starts to boil, start a timer for 2 minutes and allow it to boil.
7. Remove from heat and pour into a shallow glass pan, cover with plastic wrap, allowing the wrap to touch the surface of the frosting to prevent any sort of film forming on the top.

For the Cake:

1. Pre-heat oven to 350°F
2. In a medium sized bowl or your mixer beat the egg whites.  As they become foamy add the cream of tartar and beat on medium speed until they double in size then add 1/2 sugar about a tablespoon at a time mixing between each addition, increasing speed to high speed.  Beat until soft peaks form should take about 1-3 minutes depending on mixer. Set aside.
3. In a small bowl combine sugar, flour, baking powder, baking soda and salt and mix until combined.
4. Dissolve the cocoa powder into the boiling water and mix until there are no lumps and pour into a large mixing bowl.
5. Add melted butter, vanilla and eggs into the chocolate mixture and mix well.
6. Add flour mixture in 3 parts, mixing between additions.
7. Using a rubber spatula cut through the middle of the bowl, scrape along the bottom, lift and fold the batter over the egg whites. Rotate the bowl a quarter turn and repeat until the batter is uniform in color and there are no white streaks.
8. Grease a 9”x13” cake pan, pour batter in and bake for 30-35 minutes, checking at the 30 minute mark. 

For the Chocolate Simple Syrup

1. In a small saucepan combine water and sugar and bring to a boil.
2. Add the cocoa powder and whisk together until there are no lumps.
3. Remove from heat and add vanilla and mix.
4. Allow to cool and add desired amount to cake.