Our delicious Cake Mix Peanut Butter Bars are such a great way to make up delicious peanut butter cake bars with the help of plain yellow cake mix that is topped with a delicious chocolate frosting, talk about a perfect dessert.
Surprisingly enough, for this perfect bake sale recipe, you won’t even need semi-sweet chocolate chips to make these cake mix cookie bars.
When you use cake mixes, you can forgo the need to use any brown sugar, all-purpose flour, or any of the other list of simple ingredients.
Make sure to print or pin this recipe and store it in your recipe box for the next time you need an easy dessert recipe.
You can use natural peanut butter for this recipe, or you can even use other nut butters if you’re not a fan of the peanut flavor. If you want to add a little extra twist, you can make them into peanut butter fudge bars! The options are endless for this one. There’s nothing better than easy peanut butter cookie bars, so let’s get started!
Ingredients used to make Cake Mix Peanut Butter Bars:
Peanut Butter Bars
- Creamy peanut butter
- Water
- Large eggs
- Yellow boxed cake mix
Frosting
- Margarine softened to room temperature (or melted butter)
- Milk
- Vanilla extract
- Cocoa powder
- Powdered sugar
Equipment Needed
For this recipe, you only need a few simple kitchen tools. We recommend using the following equipment:
How to make Cake Mix Peanut Butter Bars
- Heat the oven to 350°F.
- Spray a 13 X 9-inch pan with non-stick cooking spray.
- In a large mixing bowl combine 1 cup peanut butter, water, and egg with an electric mixer until the batter is smooth. Stir in cake mix until blended well in the large bowl. Spread into prepared pan.
- Bake 20-25 minutes or until puffed and light golden brown. Cool completely.
- Mix all ingredients with a hand mixer until smooth. Add more powdered sugar or milk until you reach desired consistency and spread the chocolate mixture on top of the bars.
Storage Suggestions
If you manage to have any leftover Bars + Brownies, these can store well if prepped appropriately. Once they have cooled completely, here is how you can store it:
- Counter: Store bars and brownies in an airtight container at room temperature for up to 4 days. If your kitchen is particularly warm, consider refrigerating instead to prevent them from getting too soft or melty.
- Refrigerator: Place in an airtight container and refrigerate for up to 1 week. Let them come to room temperature before serving for the best texture and flavor.
- Freezer: To freeze, make sure bars and brownies are completely cooled and unfrosted. Wrap tightly in plastic wrap (or Press & Seal) and then place in a freezer-safe bag or container. For easier portioning, wrap individual squares before freezing. Don’t forget to label with the date. They’ll stay fresh in the freezer for up to 3 months.
Tip for making our cake mix cookie bar recipe:
You can make these peanut butter treats even more delicious by sprinkling either some peanut butter chips or white chocolate chips on top.
Also, melting a cup of peanut butter and drizzling it over top would be fantastic.
To keep the peanut butter chocolate bars fresh, store them in an airtight container for 3-4 days. If you want the topping to harden, keep them in the fridge.
Enjoy More Delicious Bar Recipes
There’s nothing better than an easy brownie or bar recipe. Check out our comprehensive list of brownies, bars, and blondies here.
- Congo Bars
- Frosted Graham Cracker Bars
- Frosted Sugar Cookie Bars
- Gooey Golden Grahams S’mores Treats
Cake Mix Peanut Butter Bars Recipe
Ingredients
- 1 cup peanut butter
- ½ cup water
- 1 large egg
- 15.25 ounces yellow cake mix
Frosting
- ½ cup margarine, softened, 1 stick
- ¼ cup milk
- 2 teaspoons vanilla, (1-2 depending on your taste)
- 3 Tablespoons cocoa powder
- 3 cups powdered sugar
Instructions
- Heat the oven to 350°F.
- Spray a 13 X 9-inch pan with no-stick cooking spray.
- In a medium bowl combine 1 cup of peanut butter, water and egg in large bowl, stirring until smooth. Stir in cake mix until blended well. Spread into prepared pan.
- BAKE 20 to 25 minutes or until puffed and light golden brown. Cool completely.
- Mix all ingredients with a hand mixer until smooth. Add more powdered sugar or milk until you reach desired consistency and spread on top of bars.
Notes
Nutrition
Did You Make This Recipe?We’d love to hear your thoughts! Leave a review or a question in the comment section below the post.
These look amazing! I love peanut butter chocolate anything, so this is right up my alley. Love how you use cake mix- makes it so easy!
Peanut butter and chocolate is my weakness, great recipe!
This looks amazing! Can butter be used instead of margarine?
Hi Ashley, you can definitely use butter in this recipe. 🙂
Thanks, Cyd! I ended up making these bars this weekend to help celebrate our anniversary, and they turned out so delicious! The chocolate frosting is super rich, but the peanut butter cake bars aren’t, so they even each other out! We love peanut butter and chocolate around here, so I’ll make these again.
Baked these yesterday and they are great. Will bake again. Very good.
Do you mix the cake mix before you stir into peanut butter mixture
Do not make the cake. Just add the dry cake mix into the other ingredients.
Can you canned frosting for the topping
If you like canned frosting, then definitely add that for the frosting top. That is not a problem at all for this recipe.
Do you need to refrigerate this since the frosting has milk?
Refrigerate any leftovers. They should be fine being left out a few hours. But not for a long extended length of time.
Gonna have to try these that’s for sure…
Gonna have to try this that’s for sure.
I use store bought chocolate frosting,
melt it a little in the microwave
add peanut butter (your call how much)
After mixed well and melty I pour it over the warm bars
Big hit
Hi Christ. That sounds amazing! Thanks for sharing.
Can you use milk instead of water?
I’m sure milk will work great too.
Can you illiminate the frosting?
Yes, you could totally leave the frosting off if you wanted.
This is so easy but I wished I would have added mini chocolate chips to the batter. I also had to add so much more powdered sugar to the frosting. I would cut back on milk next time. My peanut butter fans are in love with this.
Do you put the frosting on the cake warm or cooled? Like Texas sheet cake frosting goes on warm cake. Thanks!
You cool these completely before frosting.
Hi, can you use a milk chocolate cake mix?
Yes, but the taste of the bars will be more chocolaty.
can these be stacked on a serving dish, or does the icing stay gooey?
The frosting will set up. You can see in the picture that we have some stacked. Let it set up before stacking. And you should be fine if you stack them 2 or possibly 3 bars high.
Sounds yummy! What size ‘weight’ cake mix did you use. I see that have all gone down in size recently.
If you scroll down to the recipe card you will see that it says a 15.25 ounce yellow cake mix. Enjoy the recipe!! It’s one of our favorites.
What do you think of using German Chocolate cake mix?
It should work fine, it would be more of a chocolate bar.
Great flavor but found the peanut butter cake portion of mine to be a bit dry….am wondering if perhaps some melted butter – perhaps at least a 1/4 cup – would help this out. May give that a try. Otherwise, great flavor!
Could you use melted chocolate chips on top instead of frosting?
We haven’t tried that but it sounds delicious!