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Last Updated on June 14, 2025 by Jennifer Osborn
Cake mix toffee bars are dangerously easy. Just five ingredients, one bowl, and zero need to drag out your mixer. With toffee bits and a buttery base, this is your new go-to dessert for bake sales, potlucks, or late-night cravings.
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: Cake Mix Toffee Bars
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Ingredients
- 1 (13.25 oz) box yellow or white cake mix
- 1 (8 oz) bag Heath bits (about 1 ⅔ cups)
- 2 large eggs
- 5 tablespoons (or ⅓ cup) melted butter
- 1 (14 oz) can sweetened condensed milk
Equipment You’ll Need
- Large mixing bowl
- Spatula or wooden spoon
- 9x13 inch baking pan
- Parchment paper (optional but helpful)
- Metal binder clips to secure parchment (pro tip)
Step-by-Step Instructions
1. Make the base
In a large mixing bowl, stir together the cake mix, one egg, and the melted butter. This dough is on the dry side, so you’ll need to work it a bit to fully combine it.
I ended up pressing a bit of the cake mix in with my hands.
2. Press into the pan
Line your 9x13 pan with parchment paper so the bars are easier to remove and slice.
If you've made my Gooey Butter Cake recipe before, you'll be familiar with using your hands to spread the cake mix over the surface of the cake pan.
I used the heavy can of sweetened condensed milk as a makeshift rolling pin to help press the dough evenly into the pan.
3. Make the topping
In the same mixing bowl, stir together the remaining egg and the full can of sweetened condensed milk until smooth.
Add the Heath bits and stir until evenly combined.
4. Assemble:
Pour the topping mixture over the cake base. Spread the topping gently to cover the entire surface.
5. Bake
Bake the bars at 350°F for 25 to 30 minutes. You’ll know it’s done when:
- The edges are golden brown and slightly pulling away from the pan.
- The topping has turned a caramel brown color.
- Your kitchen smells amazing.
- A digital thermometer reads at least 200F° when you insert it in the center of the bars.
6. Cool Bars
Let cool at room temperature for about an hour before slicing. Toffee bars are easier to slice than most other bars, like my S'mores Bars recipe or Crunchy Sweet Salty Bars .
Toffee Bar Recipe Tips
- The base is fairly dry, so you’ll need to work it into the pan. Next time I make these, I’ll probably bump up the butter slightly — closer to a full stick — to make spreading even easier.
- For nice, clean cuts, I like to use a bench scraper instead of a knife. The flat, wide blade makes it easy to press straight down and get perfect wedges.
Storage Instructions
- Store tightly covered at room temperature for up to 3 days.
- For longer storage, double-wrap the bars and freeze. You should be able to freeze for up to two months.
Recipe Variations
- You can experiment with different cake mix flavors—chocolate cake mix would be phenomenal.
- I don’t recommend doubling the recipe as written; it likely wouldn’t bake evenly.
- I haven’t tested a gluten-free version, so I can’t speak to how it would turn out.
Cake Mix Recipes
If you love cake mix recipes, try baking St. Louis Gooey Butter Cake , Cake Mix Snickerdoodles , Kentucky Butter Cake Cookies and Gooey Butter Cake Cookies.
One of the most popular cookie recipes on Kitchen Serf is Chewy Toffee Cookies , a must bake for toffee lovers. Those were so good I made a Chocolate Toffee cookie and a Toffee Doodle, a cookie that's half snickerdoodle/half toffee!
Sweetened Condensed Milk Desserts
Sweetened condensed milk is the secret ingredient for many desserts, including Cake Mix Toffee Bars, S'mores Bars , Salty, Sweet and Crunchy Bars , Key Lime Bars and Lemon Bars with Graham Cracker Crust.
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Recipe
Cake Mix Toffee Bars
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Cake Mix Toffee Bars are your delicious solution for potlucks, bake sales, holiday trays, or anytime you need an easy, sweet treat fast.
Ingredients
- 1 (15.25 oz) box yellow cake mix
- 1 and ⅔ cups Heath bits (that’s one 8 oz package)
- 2 large eggs
- 5 tablespoons (or ⅓ cup) melted butter
- 1 (14 oz) can sweetened condensed milk
Instructions
Make the base:
In a large mixing bowl, stir together one large egg, the cake mix, and the melted butter. No need to pull out your mixer—this comes together quickly by hand. Stir for a minute or two until the mixture is fully combined. It will be fairly dry and crumbly, similar to my gooey butter cake dough, if you've made that before.
Press into pan:
Line a 13x9 inch pan with parchment paper (I like to clip the parchment to the sides of the pan with metal binder clips to keep it in place). Pour the dough into the pan. Because it’s thick, you’ll need to work it into an even layer. I actually used my unopened can of sweetened condensed milk as a little rolling pin to help press and smooth it out—it works surprisingly well! Then use your fingers to finish spreading the dough, making sure the whole bottom is covered with no gaps.
Mix the topping:
In the same bowl, add the remaining egg and the entire can of sweetened condensed milk. Stir or whisk until smooth and no yellow streaks remain—it should be pale and creamy. Stir in the Heath bits (or chopped Heath bars), mixing just until evenly combined.
Assemble:
Pour the topping mixture over the cake base. Gently spread it to make sure the entire surface is covered—this layer will be fairly thin.
Bake:
Preheat your oven to 350°F. Bake for 20 minutes, then check. Mine needed 30 minutes total. You’ll know it’s close when your kitchen smells like chocolatey cake heaven. The edges should be golden brown and the topping will turn a caramelized, toffee color as the chocolate melts.
Check for doneness:
Since there’s egg in the topping, you want it baked through. Aim for an internal temperature of 200°F for food safety.
Cool and chill:
Let the bars cool at room temperature for an hour. For clean, pretty slices, refrigerate for at least another hour until fully chilled and set. If you don’t care about perfect squares, you can totally dig in once it’s cool enough not to scorch your tongue.
Notes
The base is fairly dry, so you’ll need to work it into the pan. Next time I make these, I’ll probably bump up the butter slightly — closer to a full stick — to make spreading even easier.
For nice, clean cuts, I like to use a bench scraper instead of a knife. The flat, wide blade makes it easy to press straight down and get perfect wedges.
Nutrition Information
Yield 24 Serving Size 1Amount Per Serving Calories 114 Total Fat 4g Saturated Fat 2g Trans Fat 0g Unsaturated Fat 1g Cholesterol 22mg Sodium 186mg Carbohydrates 19g Fiber 0g Sugar 10g Protein 1g
Nutrition information is an estimate as I am not a registered dietician.
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