Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add the milk, vegetable oil, eggs, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes until well combined.
Carefully stir in the boiling water. The batter will be thin; this is normal.
Divide the batter evenly between the prepared cake pans.
Bake for 30 to 35 minutes or until a toothpick inserted into the center comes out clean.
Remove the cakes from the oven and allow them to cool in the pans for 10 minutes.
Turn the cakes out onto wire racks to cool completely.
To prepare the frosting, beat the softened butter in a large bowl until creamy.
Gradually add the powdered sugar and cocoa powder, beating on low speed until combined.
Add the milk and vanilla extract and beat on high speed for 3 minutes until the frosting is light and fluffy.
Place one cake layer on a serving plate. Spread a layer of frosting on top.
Place the second cake layer on top and frost the top and sides of the cake evenly.
Decorate the cake with assorted Easter-themed decorations as desired.
Refrigerate the cake for at least 30 minutes before serving to set the frosting.