Indulge your sweet tooth with these fudgy peanut butter bars. A layer of decadent fudge is sandwiched between layers of rich peanut butter dough... and it all starts with a box of cake mix.
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This post was originally published in August 2019 and has been updated.
As a child, I frequently enjoyed after-school treats like these fudge-filled peanut butter bars. I loved coming home to the aroma of peanut butter wafting from the oven.
As an adult, I love scrumptious desserts that are easy to make. These bars start with cake mix, a shortcut ingredient that I love using in other sweet treats, such as these Spice Cake Mix Cookies, my Vanilla Almond Cake with Marshmallow Buttercream, and this decadent Heath Bar poke cake.
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Why you will love these bars
- Using a cake mix adds ease and convenience.
- Just six ingredients stand between you, these bars, and a tall glass of milk.
- Easy to make - no electric mixer required.
- Chocolate and peanut butter are always a winning combination, like in these white chocolate peanut butter cups.
- It makes a large 9x13 pan (24 bars) - perfect for bake sales, potlucks, or feeding a crowd.
Ingredient notes and substitutions
- Sweetened condensed milk is one of the most wonderful baking ingredients. It adds a deliciously sweet, rich, and creamy consistency.
- Chocolate chips and peanut butter chips - I like the combination of dark chocolate and peanut butter chips. You can substitute milk chocolate or semi-sweet chips for dark chocolate. You can also omit the peanut butter chips and use only chocolate chips. You will need 1 ¾ cups total.
- Peanut butter - I used Skippy creamy peanut butter. If you want to add texture to the bars, try chunky peanut butter. Avoid using reduced-fat peanut butter. The consistency is very different, affecting the bars' consistency.
Recipe note
The original recipe from my childhood included Coconut Pecan Frosting mix as an optional addition to the fudge filling. Since this frosting mix is no longer readily available, I've omitted it from the recipe, and I love the result.
If you wish to add texture to the fudge filling, stir in some shredded coconut and chopped pecans.
Step-by-Step Instructions
Please see the recipe card for complete instructions and ingredient amounts.
Line a 9x13-inch pan with parchment paper, leaving an overhang on two sides, similar to a sling.
- Combine cake mix, peanut butter, eggs, and melted butter in a large mixing bowl.
- Stir until fully combined.
- Press ⅔ of the dough into the bottom of the cake pan. Set aside.
- Combine sweetened condensed milk, chocolate chips, peanut butter chips, and butter in a small saucepan. Heat over low until the chips are melted and the mixture is smooth. The mixture will be thick.
- Spread the chocolate mixture evenly over the dough in the prepared pan.
- Using your fingers, arrange the remaining dough pieces over the top of the chocolate.
- Bake until set and lightly golden brown.
- Cool completely before slicing.
Expert Tips
- Line the baking pan with parchment paper to help lift the cooled bars out of the pan for easy slicing.
- When lining with parchment paper, spray the bottom of the pan with cooking spray first. This will hold the parchment in place while pressing the dough into the pan.
- Chill the bars before slicing. Once the bars have cooled to room temperature, chill them for another 15-20 minutes. This makes it much easier to remove them from the pan and neatly slice them into squares.
- These bars are rich, so I like to cut them into 24 smaller squares.
- I love using this 5 wheel pastry cutter to make evenly cut squares.
Recipe FAQs
Chocolate morsels or baking chocolate can be used. Chop the baking chocolate to measure 1 cup. Do not use unsweetened baking bars.
No, I do not recommend reduced-fat varieties. They are different in consistency and will not yield the same final result.
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📖 Recipe Card
Cake Mix Peanut Butter Fudge Bars
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EQUIPMENT
Ingredients
Dough
- 1 box (15.25 ounces) yellow cake mix
- 1 cup creamy peanut butter (Note 1)
- ½ cup unsalted butter (melted)
- 2 large eggs
Filling
- 1 cup dark chocolate chips (or milk or semi-sweet chocolate)
- ¾ cup peanut butter chips
- 14 ounces sweetened condensed milk
- 2 tablespoons unsalted butter
Instructions
- Preheat the oven to 350℉. Line a 9x13-inch baking dish with parchment paper allowing it to hang over on two sides, like a sling. (Note 2)
- In a large mixing bowl, combine the cake mix, peanut butter, eggs, and ½ cup melted butter. Stir until the dough comes together. Press ⅔ the dough into the prepared pan. (Save the remaining dough to use as the topping.) Set aside.
- In a small saucepan, combine the chocolate and peanut butter chips, sweetened condensed milk, and 2 tablespoons of butter. Melt over low heat, stirring constantly, until melted and combined. Spread this mixture over the dough in the pan. Using your fingers, arrange pieces of the remaining dough over the top of the filling.
- Bake for 20-25 minutes until light golden brown. Cool completely before cutting into squares. Store in an airtight container.
Notes
- Do not use reduced-fat peanut butter. The consistency will not be the same.
- Spray the pan with cooking spray before lining it with parchment paper. This will hold the parchment in place, making it easier to spread the dough in the pan.
- After cooling the bars to room temperature, chill them for another 15-20 minutes. This makes it easier to lift them from the pan and neatly slice them.
- Store in an airtight container for up to 5 days.
Nutrition
Nutritional information is an estimate and will vary depending on the exact amounts and specific ingredients used.
Sharon Fish says
I have modified the recipe to use ready made coconut pecan frosting.
For the filling:
Leave out the condensed milk and the butter.
Use one container coconut pecan frosting and a 12 oz pkg of chocolate chips.
Melt and stir and spread on top of the bottom cake mix layer.
Abbey says
Sounds delicious! I remember my mother using the ready-made coconut pecan frosting in these bars, but I have a hard time finding it. Thank you for sharing!