Ingredients:

  • 2 cups All-Purpose Flour (Sifted)
  • ¾ cup Unsweetened Cocoa Powder (Dutch-processed)
  • 1 teaspoon Baking Soda
  • 1 teaspoon Fine Sea Salt
  • 1 cup Unsalted Butter, softened (for cake)
  • 1 ¾ cups Granulated Sugar
  • 3 Large Eggs (Room temperature)
  • 1 teaspoon Vanilla Extract
  • 1 cup Buttermilk (Room temperature)
  • ½ cup Strong Black Coffee (Hot, freshly brewed)
  • ½ cup Nutella (for cake swirl/filling)
  • ½ cup Unsalted Butter, softened (for frosting)
  • 3 cups Powdered Sugar (Sifted)
  • 1 cup Nutella (for frosting)
  • ¼ cup Heavy Cream
  • ¼ teaspoon Salt (for frosting)

Instructions:

  1. Prep: Preheat the oven to 350°F (175°C). Grease and line two 8-inch (20 cm) cake pans with parchment paper circles.
  2. Combine Dry Ingredients: Sift together the flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
  3. Cream Butter and Sugar: In a large bowl or stand mixer, cream the softened butter (1 cup) and granulated sugar until light, pale, and fluffy (about 3-4 minutes).
  4. Add Wet Ingredients: Beat in the eggs one at a time, followed by the vanilla extract. Mix in the buttermilk until just combined.
  5. Incorporate Dry: Gradually add the sifted dry ingredients to the wet mixture, mixing on low speed until just combined. Do not overmix.
  6. The Hot Liquid Trick: Slowly pour in the hot coffee while mixing on the lowest speed. The batter will be thin, which is correct. Scrape down the sides of the bowl.
  7. Divide and Swirl: Divide the batter evenly between the two prepared pans. Gently dollop ¼ cup of Nutella onto the surface of each cake batter. Use a skewer or knife to gently swirl the Nutella through the top layer of the batter.
  8. Bake: Bake for 30–35 minutes, or until a skewer inserted into the centre comes out clean (avoiding the visible Nutella swirl).
  9. Cooling: Let the cakes cool in the pans on a wire rack for 10 minutes. Invert them onto the rack, peel off the parchment paper, and allow them to cool completely—about 45 minutes—before frosting.
  10. Make Buttercream: Beat the softened butter (½ cup) on medium speed until creamy and pale (about 2 minutes). Gradually add the sifted powdered sugar, alternating with the heavy cream, beating until smooth.
  11. Finish Buttercream: Beat in the cup of Nutella and the pinch of salt until the frosting is light, fluffy, and spreadable. Adjust consistency with small splashes of cream if needed.
  12. Assembly - Level and Layer: If the cake domes excessively, level the tops. Place the first cake layer on your serving plate. Spread about ⅓ of the buttercream evenly over the top.
  13. Crumb Coat: Place the second layer on top. Apply a thin layer (a 'crumb coat') of frosting over the entire cake to lock in any loose crumbs. Chill the cake for 15 minutes.
  14. Final Frost: Apply the remaining buttercream, smoothing the sides and top with an offset spatula. Garnish optionally with melted Nutella and chopped hazelnuts.