Peanut butter brownies from brownie mix are an easy way to upgrade boxed brownies. You get rich, fudgy brownies with swirls of sweet and salty peanut butter - all made with simple ingredients and just a few easy steps.
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Ingredients You'll Need
Brownie base ingredients
Extra ingredients
Notes and Substitutions
- Brownie mix: Use one regular box (about 18 ounces). Any brand works.
- Peanut butter: Creamy peanut butter is easiest to swirl.
- Water: You can use milk, buttermilk, or brewed coffee instead for richer brownies.
- Instant coffee: Optional, but it makes the chocolate taste stronger and keeps the brownies from tasting too sweet.
Tips for Best Brownies
- Let eggs come to room temperature, then lightly beat before adding. This helps everything mix evenly.
- Grease the pan and line with parchment so the brownies don't stick.
- Start checking with a toothpick about 2 minutes early. A few moist crumbs mean fudgy brownies; a cleaner toothpick means more cake-like.
- Let brownies cool before cutting. Chill them first if you want cleaner slices.
How to Make Peanut Butter Brownies from Brownie Mix:
Step 1: Prepare the brownie batter according to the package directions. Spread it evenly in a 9×9-inch pan.
Step 2: In a small bowl, mix ¾ cup peanut butter and ¼ cup powdered sugar until smooth. If the peanut butter is thick, warm it in the microwave for a few seconds to make it easier to stir.
Step 3: Spoon dollops of the peanut butter mixture over the brownie batter. Use a knife or skewer to gently swirl it in.
Step 4: Bake according to the package directions.
Let the brownies set for at least an hour in the fridge before cutting.
Storage
Store brownies covered in the refrigerator for up to 5 days. Let them sit at room temperature for a few minutes before serving.
Recipe FAQs
Yes. Any regular brownie mix works - just follow the package directions.
Creamy peanut butter is easiest to swirl and gives the smoothest texture.
Insert a toothpick into the brownie part. A few moist crumbs mean fudgy brownies; a clean toothpick means more cake-like.
Yes. Bake them a day ahead and store covered in the fridge. Let sit at room temperature before serving.
More Tips for Boxed Brownies
If you're new to baking with brownie mix, this guide covers common questions, extra tips, and easy fixes.
Other Cakes and Baked Desserts You May Like
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📖 Recipe
Peanut Butter Brownies from Brownie Mix
Equipment
- 9x9-inch pan
Ingredients
Brownie base
- 1 box brownie mix (about 18 ounces)
- eggs room temp & lightly beaten (see box for amount)
- water sub:milk, buttermilk, or coffee (see box for amount)
- oil (see box for amount)
- ½ teaspoon instant coffee or ¼ teaspoon espresso powder (optional)
Peanut butter mixture
- ¾ cup creamy peanut butter salted (or add a pinch of salt)
- ¼ cup powdered sugar
Instructions
- Prepare the brownie batter according to the package directions. Spread evenly in a 9×9-inch pan.
- In a small bowl, mix the peanut butter and powdered sugar until smooth. If thick, warm in the microwave for a few seconds.
- Spoon dollops of the peanut butter mixture over the brownie batter. Use a knife or skewer to gently swirl.
- Bake according to the package directions.
- Let cool, then chill for about 30 minutes before cutting for cleaner slices.
Notes
- Brownie mix: Any brand works.
- Peanut butter: Creamy peanut butter is easiest to swirl.
- Water: You can use milk, buttermilk, or brewed coffee instead for richer brownies.
- Instant coffee: Optional, but makes the chocolate taste stronger and keeps brownies from tasting too sweet.
- Line the pan with parchment so brownies don't stick.
- Start checking a few minutes early to avoid overbaking.
- A toothpick with a few moist crumbs means fudgy brownies.
- Chill before slicing for cleaner cuts.
Cara says
Oh what a great combination. I’m also thinking of mixing in some reese’s pieces..
Nora Rey says
Oh, absolutely! That sounds like an amazing addition! 🤩 Combining Reese's Pieces will take it to a whole new level of deliciousness! You've got a fantastic idea there. Let me know how it turns out.