Preheat the oven to 350 degrees F (175 degrees C). Grease and flour two 9-inch springform pans.
Combine flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl. Make a well in the center and add eggs milk, oil, and vanilla extract. Beat with an electric mixer on medium speed until well combined, about 2 minutes. Stir in boiling water. divide batter between the prepared springform pans.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 35 minutes. Cool in the pans on ire racks for 10 minutes. Run a table knife around the edges to loosen. Invert carefully onto wire racks. Let cool completely, about 30 minutes.
Cream together butter and vanilla extract in a large bowl. Blend in confectioner's sugar, 1/2 cup at a time, until fully incorporated. Beat in milk until frosting is light and fluffy. Keep icing covered until ready to decorate.
Place 1 whole cooked cake on a serving tray for the bunny's head. Cut 2 convex-shaped ears from each side of the second cake place. Place ears on each side of the head. Use the remaining concave-shaped piece for the bowtie; position it about 1/2 inch below the head.
Spread frosting over the entire cake. Sprinkle with flaked coconut to make the surface look like fur. Decorate the bunny face and bowtie with candy decorations and use the black decorating icing to draw on whiskers.