Peanut Butter Brownies

Brownies one of those desserts that never let you down. Whether it’s a school bake sale, a last-minute family gathering, or a Saturday night when the kids are begging for “something sweet,” brownies always step up to the plate.

Now, when you take that classic chocolatey goodness and swirl in creamy peanut butter? Oh, friend you’ve just unlocked a whole new level of comfort food magic.

This recipe is easy to make. The best part? It all starts with a simple box mix. No shame here! In fact, I consider boxed mixes one of my secret kitchen superpowers. With just a few tweaks, you can make them taste like you’ve been baking from scratch all afternoon.

Peanut Butter Brownies Recipe

Step-by-Step Instructions

Step 1: Mix the base
Empty your brownie mix into a bowl. Add the egg, water, and vegetable oil. You can whisk it by hand if you’re in the mood for a little arm workout, or let the electric mixer do the heavy lifting.

Step 2: Prepare your pan
Line your 8×8 tin with parchment paper. I like to leave a little overhang on the sides so I can lift the whole brownie block out later without fighting with the corners of the pan.

Step 3: Pour and swirl
Pour the brownie batter into your lined tin, spreading it evenly with a spatula. Now comes the fun part drizzle your peanut butter right over the top. Use as much or as little as you like. I usually go for at least 2 big spoonfuls, sometimes even 4, depending on how indulgent I’m feeling.

Take a butter knife and gently swirl it through the batter to create those beautiful marbled ribbons of peanut butter.

Step 4: Bake to perfection
Pop your tin into a preheated oven at 320°F (160°C) and bake for 15–18 minutes. The key is to check with a toothpick if it comes out clean or with just a few moist crumbs, you’re good to go. Don’t overbake or you’ll lose that fudgy magic.

Step 5: Cool and slice
Let your brownies rest on a cooling rack for at least 10–15 minutes. This part is always torture because the house smells incredible, but it’s worth the wait cutting into hot brownies often leads to a gooey mess. Once cooled, lift them out using your parchment paper, slice into squares, and enjoy.

Why These Brownies Are a Family Favorite

These peanut butter brownies check all the boxes:

• Quick and easy – 30 minutes from start to finish.
• Kid-friendly – My kids love helping swirl the peanut butter. Sometimes they even make little “artwork” patterns with it.
• Crowd-pleasing – Chocolate + peanut butter is one of those combos that just works. Everyone loves it.
• Portable – Perfect for lunchboxes, potlucks, or wrapped in foil for a road trip snack.

Tips for the Best Peanut Butter Brownies

1. Don’t skimp on the peanut butter. If the box only gives you a tiny pouch, grab your jar and add extra. The creaminess really elevates the brownies.
2. Use parchment paper. It makes life so much easier when it’s time to cut and serve.
3. Fudgy vs. cakey. If you like your brownies extra fudgy, pull them out closer to the 15-minute mark. If you prefer a firmer bite, go for 18–20 minutes.
4. Swirl gently. Overmixing the peanut butter into the batter can make it disappear. Just a few swipes of the knife will give you that beautiful marbled effect.
5. Let them cool. I know, I know it’s hard to wait. But trust me, clean slices and rich flavor are worth it.

Fun Variations

One of the reasons I love this recipe is how adaptable it is. Here are a few fun twists you can try:

• Chocolate Chips: Sprinkle a handful of chocolate chips into the batter before baking for an extra layer of gooey goodness.
• Nutty Crunch: Add chopped peanuts on top for a little crunch.
• Salted Peanut Butter Swirl: Sprinkle sea salt over the peanut butter swirl before baking. Sweet + salty = irresistible.
• Double Trouble: Drizzle melted chocolate on top of the baked brownies for a bakery-style finish.
• Peanut Butter Cups: Chop up mini peanut butter cups and stir them into the batter for the ultimate indulgence.

Serving Ideas

These brownies are wonderful on their own, but if you want to take them over the top:

• Warm a square in the microwave and top with a scoop of vanilla ice cream.
• Drizzle with extra peanut butter or chocolate sauce.
• Serve with a tall glass of cold milk for that nostalgic, after-school-snack vibe.
• Pack them in little gift bags for neighbors or teachers homemade treats always bring a smile.

If you’re looking for a dessert that’s easy, foolproof, and guaranteed to please, these Peanut Butter Brownies are it. They’re the perfect blend of chocolatey richness and creamy peanut butter, ready in under 30 minutes, and always a hit with both kids and adults.

So next time you need something quick for a party, a school event, or just a little pick-me-up on a rough day, pull out that box mix and your trusty jar of peanut butter. I promise you won’t regret it.

Now, the only question left is: will you cut them into neat little squares… or just grab a fork and eat straight from the pan? (No judgment here I’ve done both!)

View More Brownie Recipes

• Easter Egg Brownies
• Christmas Rudolph Brownies
• Chocolate Pumpkin Patch Brownie Cake

Peanut Butter Brownies

Print Recipe Pin Recipe

Ingredients

  

• 1 box peanut butter brownie mix any brand you love
• 1 egg
• 2 tablespoons water
• 2 tablespoons vegetable oil
• 2-4 tablespoons peanut butter the pouch that comes in the box works, but you can always add more from the jar trust me, extra peanut butter never hurts!
• 8×8 inch square baking tin
• Parchment paper for easy cleanup and neat slices

Instructions

 

• Empty your brownie mix into a bowl. Add the egg, water, and vegetable oil. You can whisk it by hand if you’re in the mood for a little arm workout, or let the electric mixer do the heavy lifting.
• Line your 8×8 tin with parchment paper. I like to leave a little overhang on the sides so I can lift the whole brownie block out later without fighting with the corners of the pan.
• Pour the brownie batter into your lined tin, spreading it evenly with a spatula. Now comes the fun part drizzle your peanut butter right over the top. Use as much or as little as you like. I usually go for at least 2 big spoonfuls, sometimes even 4, depending on how indulgent I’m feeling.
• Take a butter knife and gently swirl it through the batter to create those beautiful marbled ribbons of peanut butter.
• Pop your tin into a preheated oven at 320°F (160°C) and bake for 15–18 minutes. The key is to check with a toothpick if it comes out clean or with just a few moist crumbs, you’re good to go. Don’t overbake or you’ll lose that fudgy magic.
• Let your brownies rest on a cooling rack for at least 10–15 minutes. This part is always torture because the house smells incredible, but it’s worth the wait cutting into hot brownies often leads to a gooey mess. Once cooled, lift them out using your parchment paper, slice into squares, and enjoy.