To a medium-sized bowl, add in the yellow cake mix, water, butter, and egg. Mix well for about two minutes. This mixture will be crumbly.
Line an 8x8 baking dish with parchment paper and spray it with nonstick spray. Press about 2/3rd of the crust mixture to the bottom of the baking dish, leaving about 1/3 of the crust to use later. Bake for 11 minutes.
While baking, start on the caramel layer. To a microwave-safe bowl, add in the caramel bits and heavy cream and microwave for 30 seconds at a time, stirring after every time, until the caramel is melty.
Once the crust has baked for 11 minutes, take it out of the oven and pour the caramel over the top. Spread it out evenly over the crust. Sprinkle the remaining 1/3 of crust evenly over the caramel and return to the oven.
Bake for 13-15 minutes or until the top crumble is golden. Let cool completely, then cut into bars and serve. Enjoy!