Tiramisu | America's Test Kitchen

Ingredients

• 2 1/2 cups strong black coffee , room temperature
• 1 1/2 tablespoons instant espresso powder
• 9 tablespoons dark rum
• 6 large egg yolks
• 2/3 cup sugar
• 1/4 teaspoon table salt
• 1 1/2 pounds (680 grams) mascarpone cheese
• 3/4 cup heavy cream (cold)
• 14 ounces (397 grams) ladyfingers (42 to 60, depending on size)
• 3 1/2 tablespoons cocoa , preferably Dutch-processed
• 1/4 cup semisweet or bittersweet chocolate , grated (optional)