Preheat oven to 350 degrees F. Line 2 muffin pans with paper liners; set aside.
Into a medium bowl, sift together flour, baking powder, baking soda, and salt; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat the eggs and sugar on medium speed for 1 minute.
In a separate bowl, mix together the vanilla, oil, and buttermilk.
With the mixer on low speed, add the flour mixture in 3 parts, alternating with the liquids; beat until combined after each addition, scraping down the sides of the bowl as needed.
Divide the batter evenly between the cups so that each is two-thirds full. Bake, rotating halfway, until a toothpick inserted into the center of a cupcake comes out clean, about 15 to 18 minutes. Transfer cupcakes to a wire rack to cool.
Chocolate Frosting: Melt chocolate chips in a double boiler; stir occasionally until smooth, about 5 minutes.
In a separate bowl, stir together the cocoa and boiling water. Let both the chocolate and the cocoa mixture cool to room temperature.
In the bowl of an electric mixer fitted with the paddle attachment, beat the butter, sugar, and salt on medium-high speed until light and fluffy. Add the melted chocolate on low speed, and then beat in the cocoa mixture.
To Assemble: Pipe frosting onto cupcakes. Let frosting set for 5 minutes. Decorate the cupcakes by placing a Ghirardelli Chocolate Bunny on top of the frosting.
