• Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line them with parchment paper.
• In a large mixing bowl, sift together the all-purpose flour, cocoa powder, baking powder, and sugar. Set aside.
• In a separate bowl, whisk together the eggs, mayonnaise, vegetable oil, and vanilla extract until well combined.
• Slowly add the wet ingredients into the dry ingredients and mix until smooth.
• Gradually stir in the boiling water. The batter will be thin, but that's perfectly fine as it ensures a moist cake.
• Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
• Let the cakes cool in the pans for about 10 minutes before transferring them to a wire rack to cool completely.
• Once the cakes are completely cooled, spread your favorite chocolate frosting over the top and sides of the cakes.
• Slice and enjoy your rich, moist, homemade Copycat Portillo’s Chocolate Cake!

How To Make Frosting:

• In a small saucepan, combine the cocoa powder and milk. Heat over low-medium heat, stirring constantly until the cocoa powder is fully dissolved and the mixture is smooth. Let it cool slightly.
• In a large mixing bowl, beat the softened butter with an electric mixer until light and fluffy (about 2-3 minutes).
• Gradually add the cooled cocoa and milk mixture to the butter, mixing well until combined.
• Slowly add the powdered sugar, one cup at a time, until the frosting thickens. After each addition, beat the frosting to ensure it’s smooth. Add the vanilla extract and a pinch of salt. Mix again until fully incorporated.
• If the frosting is too thick, add a little more milk (1 tablespoon at a time) until you reach the desired consistency. If it’s too thin, add a little more powdered sugar.
• Once your cake has cooled completely, spread the frosting generously over the top and sides of the cake.