Preheat your oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick cooking spray.
Mix the devil's food cake mix according to the package directions, adding the required water, oil, and eggs.
Bake the first layer. Pour half of the cake batter into your prepared baking dish. Bake for 10–15 minutes. My oven usually takes about 10 minutes, but yours may need a few minutes longer.
Prepare the caramel mixture. While the cake is baking, combine the entire jar of caramel ice cream topping and the can of sweetened condensed milk in a microwave-safe bowl. Stir well and microwave for about 20 seconds to make the mixture easier to pour.
Add the chocolate chips and caramel. Remove the baked cake from the oven. Sprinkle the chocolate chips evenly over the cake. Pour half of the caramel and sweetened condensed milk mixture over the chocolate chips. Use a spatula to spread it evenly.
Add the remaining cake batter. Carefully pour the remaining cake batter over the caramel layer. Spread it gently and evenly over the top.
Finish baking. Return the cake to the oven and bake for another 10–15 minutes, or until the cake is baked through. Baking times can vary depending on your oven, so check for doneness with a toothpick.
Add the remaining caramel topping. Remove the cake from the oven. While it's still warm, use toothpicks or wooden skewers to poke holes throughout the cake. I like to use one in each hand to make this step go a little faster! Pour the remaining caramel and sweetened condensed milk mixture over the top, allowing it to soak into the holes. Gently spread it around with the spatula.
