First, make the chocolate cake:

1. Prepare. Preheat the oven to 180°C (350°F). Butter a 20cm (10*4 inch) springform pan and line with parchment paper. Sift together the flour, baking powder and cocoa powder in a medium-sized bowl. Put the chocolate chips on a plate, covered with baking parchment, in a single layer and place in the freezer. This way the chocolate chips won’t melt too much while baking.

2. Make the batter. In a large mixing bowl, use the whisk to mix the eggs and vanilla extract until light and fluffy, about 2 min. Add the milk and oil and continue whisking until combined. Gradually add the sifted dry ingredients and mix until combined. Using a spatula fold in the cold chocolate chips. Pour the batter into the lined pan and smooth the surface evenly.

3. Bake. Bake for 45 min or until a wooden toothpick inserted into the cake comes out clean. Set the pan on a wire rack to cool for 15 min, then unmold your simple chocolate cake directly onto a rack. If you want to glaze or ice the cake, wait for it to be completely cold first.

Then make the chocolate ganache:

1. Make the ganache. Put the chocolate chips/pieces in a bowl. Put the cream in a saucepan over medium heat and bring it to just below a boil, stirring from time to time. Take the pan off the heat and pour the cream over the chocolate. Stir gently with a spatula until completely blended.

2. Glaze the cake. Scrape the glaze into a pitcher and pour it over the cooled chocolate cake, allowing it to drip down the sides.

    

Optionally, make the green icing:

1. Make the green icing. Put the softened butter and the vanilla extract in a big mixing bowl. Mix with a hand mixer on low speed until fully combined. Add the powdered sugar to the mixing bowl. Mix, still on low speed, until combined then increase the speed to medium for 30 seconds. Scrape the side of your mixing bowl and add the food coloring.

2. Check the consistency. Mix on low speed and check if the icing is coming together. Add the milk if it doesn’t come together. You might need to gradually add more milk if it still seems too dry for you.

3. Ice the cake. When the icing is the proper consistency, scrap it in a piping bag, and cut the tip. Check if the glaze has set and then write whatever you want on Hagrid’s cake.