Preheat the oven to 350°F. Prepare three 8-inch round cake pans by greasing and flouring or lining them with parchment paper.

In a medium bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt. Set aside.

In a large mixing bowl, beat the sugar and eggs on medium speed until light and fluffy, about 2–3 minutes.

Add the buttermilk, oil, and vanilla. Mix until fully combined.

Alternate adding the dry ingredients and warm coffee to the wet ingredients, mixing just until combined. Scrape the bowl and beat for one more minute.

Divide the batter evenly between the three pans (about 16 oz per pan).

Bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean.

Let cakes cool in the pans for 20 minutes, then turn them out onto a wire rack to cool completely.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter for 2–3 minutes until smooth.

Add powdered sugar one cup at a time, mixing on low after each addition.

Stir in the cream and vanilla, then scrape the sides of the bowl.

Beat on medium speed for 5 minutes until light and fluffy.

Scoop 1/2 cup of frosting into a small bowl and tint it green. Color the remaining frosting pink.

Place one cooled cake layer on a serving plate.

Spread about 1 cup of frosting or ganache on top.

Add the second layer. You can stop here or add the third layer for extra height.

Frost the outside of the cake with pink frosting. Smooth it out, but leave it slightly rough for that classic Hagrid look.

Use a spatula to drag a swirl across the top of the cake.

Fill a piping bag with the green frosting, snip the end, and carefully pipe your “Happee Birthdae” message across the top.