Preheat your oven according to the instructions on the chocolate cake mix box. Bake the chocolate cake for approximately 25 to 30 minutes, until a toothpick inserted into the center comes out clean. Once baked, allow the cake to cool completely on a wire rack before cutting it into 1-inch cubes, setting it aside for layering in your Chocolate Toffee Trifle.

In a large mixing bowl, whisk together the instant chocolate pudding mix and cold milk for about 2 minutes. Let the pudding sit for a few minutes to chill slightly.

In a trifle dish, start building your masterpiece by placing half of the cake cubes on the bottom. Spoon half of the prepared chocolate pudding over the cake, ensuring it evenly covers the surface. Add half of the whipped topping, gently spreading it. Sprinkle half of the crushed chocolate-covered toffee bars over the whipped topping.

Continue layering by repeating the steps with the remaining ingredients. Add the rest of the cake cubes, followed by the remaining pudding and whipped topping. Sprinkle the last of the crushed toffee bits on top.

Cover the assembled trifle with plastic wrap and refrigerate for at least 1 hour, up to 24 hours, to allow the flavors to meld beautifully. When ready to serve, optional garnish with chocolate curls.