1. Preparing the Cake Batter

1. Preheat the oven to 350°F (175°C).
2. In a bowl, combine the dry ingredients (flour, baking powder, salt). Set aside.
3. In a separate bowl, beat the butter and sugar until light and fluffy.
4. Add eggs, one at a time, beating well after each addition. Stir in vanilla extract.
5. Gradually add the dry ingredients, alternating with milk, until fully combined.
6. Add yellow gel food coloring to achieve the desired shade of yellow.
7. Divide the batter evenly between two round cake pans, greased and lined with parchment paper.
8. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Let the cakes cool completely.

2. Making the Black Ganache

1. Heat the heavy cream in a saucepan over medium heat until just simmering.
2. Pour the hot cream over the semi-sweet chocolate chips and stir until smooth.
3. Add black gel food coloring to achieve a bold black color. Set aside to cool.

3. Assembling the Cake Layers

1. Place one cake layer on a cake stand or serving plate.
2. Spread a thin layer of ganache over the top of the first cake layer.
3. Place the second cake layer on top and apply a crumb coat of buttercream frosting.
4. Refrigerate for 20-30 minutes to set the crumb coat.

4. Decorating the Cake

1. Frost the cake with yellow buttercream, smoothing the sides and top.
2. Drizzle black ganache over the top for a marbled effect.
3. Add optional decorations like edible gold dust or a Hufflepuff crest topper.
4. Chill until ready to serve.