Preheat oven to 350°F (175°C). In a mixing bowl, combine cake mix, eggs, water, and oil. Mix until smooth and pour into greased baking pan. Bake for 25-30 minutes until a toothpick comes out clean. Let cool.

Cut the cooled cake into bite-sized squares. Place in a dish and pour sweetened condensed milk over the cake. Let absorb for 5-10 minutes.

In a trifle bowl, layer one-third of soaked cake pieces, then one-third of whipped cream, one-third of caramel syrup, and toffee bits. Repeat until all ingredients are used.

Crush the Heath bar and sprinkle over the final layer of whipped cream.

Cover and refrigerate for at least 2 hours to allow flavors to meld.

Serve chilled, scooping out portions with a large spoon to capture all layers.