01 - Preheat the 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.
03 - Add eggs, milk, oil, and vanilla to the dry mixture. Beat on medium speed until well combined.
04 - Carefully mix in the boiling water. The batter will be thin, which is normal.
05 - Divide the batter evenly between the prepared pans.
06 - Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
07 - Let cakes cool in pans for 10 minutes, then turn out onto wire racks to cool completely.
08 - Beat butter until creamy. Sift in cocoa powder and mix well.
09 - Gradually add powdered sugar, alternating with milk, until smooth and spreadable.
10 - Add vanilla and a pinch of salt. Beat until fully combined.
11 - Place one cake layer on a serving plate. Spread a layer of frosting on top.
12 - Stack the second cake layer and cover the top and sides with the remaining frosting.
13 - For the classic Matilda look, use an offset spatula to create swoops and swirls in the frosting.