Cake Mix Cookie Bars

Thick, chewy, and super delicious, these Small Batch Cake Mix Cookie Bars are a quick and easy treat you can bake in your oven or toaster oven. With a boxed cake mix as the base, your flavor options are endless!

3 cookie bars stacked on a blue plate.

Last month I tried baking this cake mix cookies recipe in our smallest toaster oven and quickly ran into a problem.

The cookies spread (a lot) during baking. So I could only fit two on the little sheet pan. At that rate, it was going to take forever to bake a whole batch.

So I grabbed a baking pan, dumped all the batter in, and came up with a tasty solution: Small Batch Cake Mix Cookie Bars!

Boxed cake mix, egg, oil. nuts, and measuring cup of chocolate chips arranged on a table and labeled.

Recipe Ingredients

  • Half A 15.25 Cake Mix: This scaled-down version of your traditional cake mix cookie bars is made with just half a boxed cake mix.
  • Large Egg
  • Oil
  • Mix-ins: To make chocolate chip cookie-style bars we used semi-sweet chocolate chips and toasted pecans.

Step-By-Step Instructions

1. Position the cooking rack in the center of the oven and preheat it to 350°F. If using a toaster oven select the BAKE setting and use the middle or bottom position. Coat an 8 x 8-inch baking pan with oil and set aside.

Glass bowl with a fork mixing egg and oil.

2. In a large bowl whisk together the egg and oil. *Instead of dumping everything in a bowl, I find it’s easier to get things well mixed if I combine the egg and oil first.

3. Next, use a silicone spatula to stir in the cake mix until well combined. Lastly, fold in the chocolate chips and chopped pecans.

Bowl with mixed cookie batter, chocolate chips, and pecans.

4. Spread the batter into the prepared pan and smooth it into an even layer. The batter will be super thick and sticky. If you’re having trouble spreading it, lightly moisten your hands with water and press it into the pan.

Batter in an 8x8 pan spread by a spatula and a pan of baked bars.

5. Bake until the edges are golden brown and the center is set but still soft, about 14 to 22 minutes. The total baking time will depend on the type of pan and oven used. To avoid over-baking, begin checking for doneness after 12 or 13 minutes and add more time as needed.

6. To keep the bars from falling apart, cool them completely before slicing and gobbling them up!

A hand holding a cookie bar in front of a blue plate.

Toaster Oven Baking Pans

The type of pan and oven used will determine how thick the bars end up and how fast (or slow) they will bake.

Of all the batches we’ve baked, the ones cooked in an 8 x 8 square pan have turned out the best. They took about 14 to 15 minutes in our countertop oven and in our traditional ‘big’ oven.

A small baking pan next to a stack of cookie bars on parchment.

We also used the 10.75 x 7.5 cake pan from one of our toaster oven pan sets to make a batch in our convection toaster oven (temp. reduced to 325°F). Because the batter was spread out more it was ready faster, after about 12 minutes, and resulted in thinner bars.

A deeper pan will likely take longer to bake. The batch I made in our 8½ x 4½ loaf pan took about 20 minutes. While they were thick and fudgy in the middle the edges and top were way overcooked. Next time I use that pan, I’ll try lowering the temperature to 325°F.

A toaster oven pan next to small cookie bars on a piece of parchment.

Our smaller toaster oven is less wattage and tends to bake slower. The batch I made in our 8.5 x 6.5 Nordic Ware Compact Oven Pan took over 20 minutes.

Tips and Variations

Use different flavored cake mixes and mixins. Lemon cake with freeze-dried berries is perfect for spring. Spice cake with raisins and orange zest has a fun autumn vibe. And chocolate cake with a swirl of peanut butter is crazy delicious!

Baked cookie bars in an 8x8 baking pan.
Funfetti bars with white chocolate chips and freeze-dried raspberries.

The bars will continue cooking as they cool. To keep from overbaking, take the bars out of the oven once they are set but still soft.

Wait to slice them until the bars have cooled completely. I like to use a plastic knife since it’s less likely to damage the pan and makes nice even cuts.

They’re very rich. Tim and I like to cut the bars into 12 smaller pieces. Since it’s just the two of us, we usually enjoy a few and toss the leftovers in the freezer. On their own or topped with a scoop of ice cream, they make a really fun treat!

Stacked of Funfetti cake mix bars on a plate.

More Easy Cake Mix Recipes

Overhead view of a pan of baked chocolate chip cake mix cookie bars cut into pieces.

Cake Mix Cookie Bars (Half Batch)

Yield: 12 Bars
Prep Time: 10 minutes
Cook Time: 15 minutes
Total Time: 25 minutes

Transform half a cake mix into something special with these thick and chewy bars. We like to add chocolate chips and pecans but you can use whatever mixins you want!

Ingredients

  • 1 Large Egg (50 grams, weighed outside of shell)
  • 3 tablespoons (42 grams) Neutral Oil, like canola oil
  • Half a 15.25 oz Boxed Cake Mix (216 grams or 7.62 Ounces or 1⅔ cups spooned and leveled)
  • 1/3 cup (74 grams) Semi-Sweet Chocolate Chips
  • 1/4 cup (30 grams) Pecan Pieces (toasted if desired)

Instructions

  1. Position the cooking rack in the center of the oven and preheat to 350°F. If using a toaster oven select the BAKE setting and use the middle or bottom rack position.
  2. Coat an 8 x 8 baking pan with oil spray, set aside.
  3. In a large bowl whisk together the egg and oil. Stir in the cake mix until well combined. Fold in the chocolate chips and chopped pecans. (The mix will be very thick and sticky)
  4. Transfer the batter to the prepared pan and use a silicone spatula to spread it into an even layer. Alternatively, you can lightly moisten or oil your hands and press the batter into the pan.
  5. Bake until the edges are golden brown and the center is set but still soft, about 15 to 22 minutes depending on the type of pan and oven used. To avoid over-baking, begin checking for doneness after 13 or 14 minutes and add more time as needed.
  6. Allow the pan to cool completely before slicing into bars and devouring!

Notes

Oil: We’ve made these cookie bars using canola oil, olive oil, avocado oil, and grapeseed oil. An equal amount of melted and cooled butter can also be used.

Cake Mix Measurements: This recipe uses half of a 15.25-ounce boxed cake mix. You can find tips for dividing a box of cake mix here.

Mixes: Yellow cake mix has that great cake batter-style flavor but you can use any variety you want. We’ve tried Betty Crocker and Pillsbury mixes. Other brands may or may not give the same results.

Nuts: Add any type of nuts you want. We used pecans because they were in the pantry and are very tasty with chocolate. Here's how to toast nuts in a toaster oven. If you don't like nuts, omit them.

Pans: See post above for different pan ideas and baking time changes.

Convection Adjustments: Reduce the temperature to 325°F. Begin checking for doneness after 11 or 12 minutes and add more time as needed.

Storage

  • Store cooled cookie bars in a sealed container for up to 3 days.
  • To freeze cookie bars, cool them completely and add to a freezer-safe bag in a single layer. For the best flavor, eat within 3 months.
  • To defrost frozen cookie bars, leave at room temperature for about 10 to 15 minutes.

Nutrition Information:
Yield: 12 Cookie Bars Serving Size: 1 Cookie Bar
Amount Per Serving: Calories: 147Total Fat: 8.3gSaturated Fat: 1.9gCholesterol: 16mgSodium: 117mgCarbohydrates: 17.2gFiber: 0.5gSugar: 9.9gProtein: 1.9g

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