Preheat oven to 350°F. Grease a 9x13-inch baking dish with nonstick spray.
Add cake mix, pudding mix, oil, water, and eggs to a large bowl. Whisk until smooth and fully combined.
Pour batter into prepared dish and bake for 28–32 minutes, or until a toothpick comes out clean.
Use the base of a wooden chopstick to poke holes all over the warm cake. In a bowl, stir together sweetened condensed milk and 3/4 cup caramel sauce. Microwave for 20 seconds, then pour evenly over the cake.
Let the cake sit at room temp for 1 hour so the filling can soak in and the cake can fully cool.
Spread whipped topping evenly over the cooled cake. Drizzle with remaining caramel sauce and sprinkle with toffee bits.
Run a sharp knife under hot water, dry it, then make a slice. Repeat until the cake is fully sliced, then enjoy!
Notes
Note 1: Betty Crocker Super Moist Triple Chocolate Cake Mix is the best here. I’ve tried a lot, and nothing beats it.Storage: Cover the cake tightly and store in the fridge for up to 4 days. Keep it chilled since it has whipped topping. For best texture, let slices sit at room temp for 10 to 15 minutes before serving.