1. Line a 9-inch springform pan with parchment paper, and spray the sides of the pan well with nonstick cooking spray. Set aside. 
  2. Preheat the oven to 350 degrees F.  
  3. Divide the eggs, place the yolks into a small bowl, and the whites into the bowl of a stand mixer. Set aside. 
  4. Fill a small saucepan with 1 inch of water, and place over medium heat. Bring the water to a simmer. Place the chopped chocolate in a medium size heat proof mixing bowl, and place the bowl on top of the pan with simmering water. Be sure that the bottom of the bowl is not touching the water. Slowly melt the chocolate, stirring occasionally. Remove the bowl from the heat as soon as most of the chocolate has melted, and continue to whisk until the chocolate is smooth. 
  5. Add the Kerrygold Unsalted Butter and the espresso powder to the chocolate mixture, and whisk to combine.  
  6. Next, combine the room temperature egg yolks, ½ cup of the granulated sugar, and kosher salt in a separate large mixing bowl. Whisk well, then add the amaro liqueur to the egg mixture. Stir to combine thoroughly. 
  7. Pour the chocolate into the bowl with egg yolks and sugar, and whisk well, until there are no streaks of chocolate. 
  8. Whisk the egg whites in the stand mixer on medium speed for 2 minutes, until the whites are frothy and lightened up. With the mixer on medium speed, slowly stream in the remaining ½ cup of granulated sugar. Beat the egg whites and sugar until glossy soft peaks form, this should take about 5 minutes, and the mixture will look like meringue. 
  9. Add ⅓ of the egg white mixture to the bowl of chocolate, and whisk gently until completely combined. This will lighten up the chocolate. Add the remaining meringue mixture to the bowl of chocolate, and use a rubber spatula to gently fold the egg whites into the chocolate. Be careful not to deflate the egg whites. Pour the cake batter into the prepared baking pan, and smooth the top with an offset spatula. 
  10. Place the cake pan on a rimmed baking sheet to make transferring it to the oven easier. Bake the cake for 35-40 minutes until the center is just set. Allow the cake to cool completely at room temperature before serving. Top with powdered sugar for serving. 

Recipe by Lion’s Bread.