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 eggs, milk, vegetable oil, 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. Then, remove from pans and cool completely on wire racks.
To make the frosting, beat the softened butter in a large bowl until creamy.
Gradually add the powdered sugar and cocoa powder, alternating with the milk, beating to a spreadable consistency.
Add the vanilla extract and salt, and beat until smooth and fluffy.
Place one cake layer on a serving plate and 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 the Easter-themed colorful sprinkles.
Refrigerate the cake for at least 30 minutes before serving to set the frosting.