Preheat oven to 350°F (175°C). Butter and flour three 8-inch round cake pans. Sift together all-purpose flour, cocoa powder, granulated sugar, baking soda, baking powder, and salt.

In a large bowl, cream together the softened unsalted butter until light and fluffy. Add the eggs one at a time, mixing well after each addition. Mix in the buttermilk and vanilla extract.

Gradually incorporate the dry ingredients, alternating with the buttermilk, and mix until just combined. Be careful not to over-mix. Divide the batter evenly between the prepared cake pans.

Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake layers to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

To make the buttercream, beat the unsalted butter until smooth. Gradually add the powdered sugar, heavy cream, and vanilla. Beat on medium-high until light and fluffy. Add food coloring one drop at a time until you achieve a delicate light blue shade.

Fill and stack the completely cooled cake layers with the blue buttercream. To create the naked look, apply a thin layer of buttercream all over the outside of the cake. Use a large bench scraper to scrape off the majority of the frosting, allowing the cake layers to show through.

For the nest, melt your dark chocolate. Create thin layers/shards on a non-stick surface, let set, break and arrange into a rustic nest on top of the cake. Place the nest centrally.

Immediately arrange the pastel eggs within and around the chocolate nest structure for an organic composition. Let the cake set in the refrigerator for at least 30 minutes before serving for cleaner slices.