01 - Preheat oven to 350°F. Grease and line two 9-inch round cake pans with parchment paper.
02 - In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt until well blended.
03 - Add eggs, milk, oil, and vanilla to the dry mixture. Beat on medium speed until thoroughly combined, about 2 minutes.
04 - Carefully stir in the boiling water. The batter will become thin—this is normal and ensures a moist cake.
05 - Divide batter evenly between prepared pans. Bake for 30-35 minutes until a toothpick inserted in the center comes out clean.
06 - Let cakes cool in pans for 10 minutes, then turn out onto wire racks to cool completely before frosting.
07 - Beat softened butter until creamy. Sift in cocoa powder and mix until fully incorporated.
08 - Gradually add powdered sugar, alternating with milk, beating until smooth and spreadable. Mix in vanilla and salt.
09 - Place one cake layer on a serving plate. Spread frosting evenly on top. Stack second layer and cover top and sides with remaining frosting.
10 - Use an offset spatula to create swoops and swirls for the classic Matilda cake presentation.