1. 1. Preheat Oven and Prepare Pans:

      • • Position an oven rack in the center of the oven. Preheat the oven to 350°F (175°C).
      • • Grease two 8-inch or 9-inch round cake pans thoroughly with butter or cooking spray.
      • • Line the bottoms of the pans with parchment paper rounds. Grease the parchment paper as well.
      • • Lightly flour the insides of the pans (over the grease), tapping out any excess flour. This three-step process (grease-parchment-grease-flour) ensures the cakes release easily.

1. 1. Toast and Chop Black Walnuts:

      • • Spread the 1 ½ cups of black walnuts in a single layer on a baking sheet.
      • • Toast in the preheated oven for 5-8 minutes, or until they are fragrant and slightly darkened. Watch them carefully, as nuts can burn quickly. Alternatively, you can toast them in a dry skillet over medium heat for 3-5 minutes, stirring frequently.
      • • Let the toasted walnuts cool completely, then roughly chop them. Set aside.

1. 1. Combine Dry Ingredients:

      • • In a medium bowl, whisk together the 2 ½ cups of all-purpose flour, 2 teaspoons of baking powder, ½ teaspoon of baking soda, and ½ teaspoon of salt. Whisking helps to aerate the flour and distribute the leaveners evenly. Set aside.

1. 1. Cream Butter and Sugars:

      • • In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a handheld electric mixer, beat the 1 cup of softened unsalted butter on medium speed until creamy, about 1 minute.
      • • Add the 1 ½ cups of granulated sugar and ½ cup of packed light brown sugar to the butter.
      • • Beat on medium-high speed for 3-5 minutes, until the mixture is light, fluffy, and pale in color. Scrape down the sides and bottom of the bowl occasionally with a rubber spatula to ensure even mixing. This step incorporates air, which is crucial for a light cake texture.

1. 1. Add Eggs and Vanilla:

      • • Reduce the mixer speed to medium-low. Add the 4 large room-temperature eggs one at a time, beating well for about 30 seconds after each addition and scraping down the bowl as needed. Ensure each egg is fully incorporated before adding the next.
      • • Beat in the 2 teaspoons of pure vanilla extract.

1. 1. Alternate Wet and Dry Ingredients:

      • • With the mixer on low speed, add the dry ingredient mixture in three additions, alternating with the 1 cup of room-temperature buttermilk in two additions. Begin and end with the dry ingredients.

          • • Add approximately one-third of the dry ingredients and mix until just combined.
          • • Add half of the buttermilk and mix until just combined.
          • • Add another third of the dry ingredients and mix until just combined.
          • • Add the remaining half of the buttermilk and mix until just combined.
          • • Add the final third of the dry ingredients and mix until just barely combined.

      • • Important: Do not overmix at this stage. Mix only until the flour streaks disappear. Overmixing develops gluten and can lead to a tough cake.

1. 1. Fold in Black Walnuts:

      • • Remove the bowl from the mixer (if using a stand mixer). Add the 1 ½ cups of chopped, toasted black walnuts to the batter.
      • • Using a rubber spatula, gently fold the walnuts into the batter until they are evenly distributed.

1. 1. Divide Batter and Bake:

      • • Divide the cake batter evenly between the two prepared cake pans. Smooth the tops with the spatula.
      • • Bake in the preheated oven for 30-35 minutes for 9-inch pans, or 35-40 minutes for 8-inch pans. The cakes are done when they are golden brown, the edges pull away slightly from the sides of the pans, and a wooden toothpick or cake tester inserted into the center comes out clean or with a few moist crumbs attached.
      • • Start checking for doneness a few minutes before the minimum baking time, as oven temperatures can vary.

1. 1. Cool the Cakes:

      • • Once baked, carefully remove the cake pans from the oven and place them on a wire cooling rack.
      • • Let the cakes cool in the pans for 10-15 minutes. This allows them to set slightly and makes them easier to handle.
      • • After 10-15 minutes, carefully invert the cakes onto the wire rack. Peel off the parchment paper.
      • • Let the cakes cool completely to room temperature before frosting, which can take 2-3 hours. Attempting to frost warm cakes will result in melted, messy frosting.

Part 2: Preparing the Classic Cream Cheese Frosting

1. 1. Beat Cream Cheese and Butter:

      • • In the clean bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a handheld electric mixer, beat the 8 ounces of softened cream cheese and ½ cup of softened unsalted butter together on medium speed until smooth, creamy, and well combined, about 2-3 minutes. Scrape down the sides and bottom of the bowl.

1. 1. Add Powdered Sugar:

      • • Reduce the mixer speed to low. Gradually add the 3 ½ to 4 cups of sifted powdered sugar, one cup at a time, mixing until smooth after each addition. Sifting the powdered sugar prevents lumps.
      • • Once all the powdered sugar is incorporated, increase the mixer speed to medium-high and beat for 2-3 minutes until the frosting is light, fluffy, and smooth.

1. 1. Add Vanilla and Salt (and Liquid if needed):

      • • Beat in the 1 teaspoon of pure vanilla extract and ¼ teaspoon of salt. The salt enhances the flavors and balances the sweetness.
      • • If the frosting is too thick, add milk or heavy cream, 1 tablespoon at a time, beating well after each addition, until you reach your desired spreading consistency. If it’s too thin, add a little more sifted powdered sugar.

Part 3: Assembling and Frosting the Cake

1. 1. Level Cakes (Optional):

      • • Once the cake layers are completely cool, if they have domed tops, you can level them using a long serrated knife for a more professional-looking cake. Place a cake layer on a flat surface and gently saw off the domed part to create a flat surface.

1. 1. Frost the Cake:

      • • Place one cake layer, top-side down (if leveled) or top-side up, onto a cake stand or serving plate.
      • • Spread a generous layer of cream cheese frosting (about 1 to 1 ½ cups) evenly over the top of the first layer, right to the edges.
      • • Carefully place the second cake layer on top of the frosted layer, top-side down (if leveled, this provides a very flat surface for the top frosting) or top-side up.
      • • Apply a thin “crumb coat” of frosting all over the top and sides of the cake. This seals in any loose crumbs. Chill the cake in the refrigerator for 15-20 minutes to set the crumb coat.
      • • Once the crumb coat is set, apply the remaining frosting to the top and sides of the cake, using an offset spatula or a bench scraper to create a smooth or textured finish as desired.

1. 1. Garnish (Optional):

      • • Garnish the frosted cake with the ¼ cup of additional toasted and chopped black walnuts. You can press them onto the sides, sprinkle them on top, or create a decorative border.

1. 1. Chill and Serve:

      • • For the best flavor and easier slicing, it’s recommended to chill the frosted cake in the refrigerator for at least 30 minutes to an hour to allow the frosting to set.
      • • Before serving, let the cake sit at room temperature for about 20-30 minutes to allow the cake and frosting to soften slightly.