FOR THE OREO BROWNIES:
Prepare the brownie mix according to the instructions on the box or using your favorite recipe.
Pour half of the batter into an 8 inch square pan, and then place 9-10 whole Oreos in rows.
Pour the remaining brownie mix and spread it gently to cover the Oreos completely.
Bake according to the instructions on the box or your recipe.
Let cool completely before cutting into equal size pieces.
FOR THE CHOCOLATE PUDDING:
Combine the cream and milk in a medium sized bowl and warm it in the microwave for about a minute or two. Boil the water in an electric kettle.
Combine the sugar, cornstarch and cocoa powder in a medium sized saucepan. Add the 2 tablespoons of boiling water and mix to create a thick paste.
Slowly whisk in the eggs one by one, following with the warmed milk and cream, and the vanilla extract.
Put the saucepan on medium-low heat and continue whisking for about 4-5 minutes or until the mixture becomes thick and silky. The consistency should be like that of mayonnaise.
Take off the heat and add the chopped chocolate. Mix until completely melted and combined.
Pour the pudding into a bowl, and cover with clingfilm so that it's resting on the surface of the chocolate pudding. This helps in preventing a thick skin forming on the pudding as it cools.
Cool until room temperature and then place in the fridge.
FOR THE WHIPPED CREAM:
Pour the whipping/heavy cream in a cool bowl.
Add in the sugar.
Using a handheld mixer (you can also use a stand mixer) beat the whipping/heavy cream on medium speed for about 6-7 minutes until soft peaks form.
LAYERING THE TRIFLE:
Start by layering your bowl with the brownies. You can break the oreo brownies into pieces if desired.
Add a layer of chocolate pudding, followed by another layer of the oreo brownies.
Once the layers are completed top with the whipped cream, add another layer of chocolate pudding and finish by decorating with Oreos.