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 combined.
03 - Add eggs, milk, oil, and vanilla to the dry mixture. Beat on medium speed until fully incorporated and smooth.
04 - Carefully mix in the boiling water. The batter will appear thin—this is normal and ensures a moist crumb.
05 - Divide batter evenly between prepared pans. Bake for 30–35 minutes until a toothpick inserted into 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 butter until creamy. Sift in cocoa powder and mix well. Gradually add powdered sugar, alternating with milk, until smooth and spreadable. Add vanilla and salt; beat to combine.
08 - Place one cake layer on a serving plate. Spread a layer of frosting on top. Stack the second layer and cover the top and sides with remaining frosting.
09 - For the classic Matilda look, use an offset spatula to create swoops and swirls in the frosting.