Baking the Chocolate Cake:

1. Preheat oven to 350°F (175°C). Grease and line a 9-inch cake pan.
2. In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, and salt.
3. Add milk, vegetable oil, eggs, and vanilla extract, mixing until smooth.
4. Pour the batter into the prepared pan and bake for 25–30 minutes, or until a toothpick comes out clean.
5. Let cool completely before cutting into small cubes for layering.

Making the Firewhisky Custard:

1. In a saucepan over medium heat, warm heavy cream until steaming (but not boiling).
2. In a separate bowl, whisk together egg yolks, sugar, and cornstarch until pale and smooth.
3. Slowly pour half the warm cream into the egg mixture while whisking constantly to temper the eggs.
4. Return the mixture to the saucepan and cook over low heat, stirring constantly, until thickened (about 5 minutes).
5. Remove from heat and stir in Firewhisky (or vanilla extract for a non-alcoholic version). Let cool.

Assembling the Trifle:

1. In a trifle dish or individual glasses, layer chocolate cake cubes, Firewhisky custard, and fresh berries.
2. Repeat layers until the dish is full, finishing with whipped cream on top.

Adding the Finishing Touches:

1. Sprinkle edible gold glitter or gold sprinkles for a Gryffindor-worthy shine.
2. Optional: Drizzle Firewhisky caramel or add chocolate shavings for extra indulgence.