Preheat oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.

In a large bowl, cream together softened butter and granulated sugar until light and fluffy.

Beat in eggs one at a time, then stir in vanilla extract.

In a separate bowl, whisk together flour, baking powder, and salt.

Gradually add dry ingredients to the butter mixture, alternating with milk, beginning and ending with the dry ingredients.

Divide batter evenly between the three pans and bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.

Allow cakes to cool in pans for 10 minutes, then transfer to wire racks to cool completely.

Using a 3-inch circular cookie cutter, cut a hole out of the center of one cake layer.

Place one solid cake layer on a serving plate and spread a thin layer of buttercream frosting on top.

Place the cake layer with the hole on top. Fill the center cavity with the pink or blue candies.

Apply frosting to the top rim of the middle layer and place the final solid cake layer on top to seal the cavity.

Cover the entire cake with a thin crumb coat of frosting and refrigerate for 20 minutes.

Tint remaining frosting with pastel colors and apply a final layer to the cake. Garnish with chocolate Easter eggs.