For the cake:
- 3 1/2 cups flour, plus more for pans
- 4 teaspoons baking powder
- 1 1/2 teaspoons kosher salt
- 24 tablespoons unsalted butter, melted, plus more for pans
- 2 1/4 cups sugar
- 2 cups milk
- 1 tablespoon vanilla extract
- 6 eggs
For the icing:
- 2 ounces unsweetened chocolate, chopped
- 2 ounces semisweet chocolate, chopped
- 2 cups sugar
- 1 cup evaporated milk
- 6 tablespoons unsalted butter, melted
- 2 teaspoons vanilla extract
To prepare the cake:
- Heat oven to 350 degrees F.
- Butter and flour four 9-inch cake pans.
- In a large bowl, whisk together flour, baking powder and salt.
- In another large bowl, whisk together butter, sugar, milk, vanilla, and eggs.
- Pour wet ingredients over dry ingredients. Stir together just until combined; let sit for 15 minutes.
- Stir batter until smooth.
- Divide half of the batter evenly among the four prepared cake pans.
- Bake cakes for 15 minutes rotating halfway through; they should be barely browned.
- Let cakes cool in pans for 20 minutes before inverting onto wire racks.
- Clean and dry pans.
- Repeat the process of greasing and flouring pans, baking four more cakes, and allowing them to cool completely.
To prepare the icing:
- In a large saucepan over medium-high heat, bring chocolates, sugar, milk and butter to a boil.
- Stir frequently until mixture is smooth, approximately 8 minutes.
- Stir in vanilla, and remove from heat.
- Allow icing to thicken for 30 minutes.
To assemble the cake:
- Place one cake on a cake stand. Spread with 1/4 cup of icing.
- Repeat with remaining cakes leaving the top and sides uniced.
- Chill cake for 30 minutes.
- Reheat remaining icing as needed before icing the top and sides.
- Refrigerate, and serve cool.