Martha Stewart's Ultimate Chocolate Cake with Ultimate Chocolate Frosting

Ingredients

• 1 cup Valrhona cocoa, plus more for dusting
• 3/4 cup strong coffee -- boiling
• 1 cup milk at room temperature
• 2 3/4 cups cake flour (not self-rising)
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1 1/2 cups (3 sticks) unsalted butter at room temperature, plus more for pan
• 2 1/2 cups sugar
• 1 tablepsoon pure vanilla extract
• 4 large eggs at room temperature
• 3 1/2 cups confectioners' sugar
• 1 cup Valrhona cocoa powder
• 12 tablespoons (1 1/2 sticks) unsalted butter at room temperature
• 1/2 cup milk at room temperature
• 2 teas pure vanilla extract