Peanut Butter Brownies
If you’re looking for the easiest ever recipe for peanut butter brownies, you’ve come to the right place! You’ll need just 4 simple ingredients (plus water) to make this chocolatey, chewy, ridiculously more-ish brownie recipe, and even if you’re a complete novice baker, you can have a batch of these ready in less than half an hour! The secret? We’ll be using a box of peanut butter brownie mix, that you can pick up at almost any grocery store. Boxed cake and brownie mixes are one of my favorite kitchen hacks for creating super impressive bakes without spending hours in the kitchen, and no one will know if you don’t tell them!
Ingredients
- Box of chocolate peanut butter brownie mix:Â Any brand will work fine!
- Peanut butter: You might have a sachet of this included in your box mix
- Egg
- Water
- Vegetable oil
You’ll also need an 8×8 inch square tin for baking your brownies, plus parchment for lining.Â
Step-by-Step Instructions
Please note that you’ll find a printable recipe card at the bottom of this post, with all the details you need including ingredients, measurements, and the simple steps for recreating this recipe at home! Here, I’ll share some handy photos as a visual guide…Â
- Preheat your oven to 320F/160C.
- Mix brownie mix with water, egg and oil. Use an electric mixer or whisk, and blend until smooth – no lumps!Â
- Line your tin with parchment, and pour in the mixture evenly.
- Drizzle peanut butter over the mixture, using as much or as little as you like. Extra peanut butter will make them taste creamier!
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- Bake for 15-18 minutes, or until an inserted toothpick comes out clean.
- Leave to cool down on a cooling rack, then cut into squares. Enjoy!
Substitutes & Variations
These brownies are beautiful just as they are, but if you want to get a little more creative, here are some ideas that you might want to try:
- Use crunchy peanut butter instead of creamy for extra texture and a satisfying crunch in every bite.
- Stir chocolate chips into the batter for a double chocolate boost—dark chocolate for richness or milk chocolate for extra sweetness.
- Fold in chopped roasted peanuts to add even more peanut flavor and a bit of crunch.
- Sprinkle flaky sea salt on top before baking for a sweet-salty contrast that enhances the peanut butter flavor.
- Drizzle caramel sauce over the peanut butter swirl before baking for a rich, gooey twist.
- Swirl mashed banana into the batter for a peanut butter & banana combo that adds natural sweetness and extra moisture.
- Mix a peanut butter cheesecake layer (cream cheese, peanut butter, sugar, and an egg) and swirl it into the brownies for a tangy, creamy contrast.
- Fold in graham cracker pieces and top with mini marshmallows for a s’mores-inspired peanut butter brownie.
- Add crushed pretzels to the batter and press whole pretzels on top before baking for a crunchy, salty-sweet treat.
- Chop peanut butter cups or Reese’s Pieces and mix them into the batter for even more peanut butter flavor.
- Drizzle melted peanut butter and sprinkle chopped nuts on top after baking for an extra indulgent finish.
Serving Your Brownies
My favorite way to enjoy these brownies is simply with a cup of coffee when they’re fresh out the oven. If you like though, you can use them as a base for so many different desserts:
- Warm with Ice Cream – Heat up a brownie and serve with a scoop of vanilla, chocolate, or peanut butter ice cream.
- With a Glass of Milk – The perfect pairing for a classic dessert moment! My little girl loves this as a weekend treat.
- Topped with Whipped Cream – A light and creamy contrast to the rich brownies.
- With a Dusting of Powdered Sugar – A simple way to make them look extra special!
- Layered into a Brownie Sundae – Chop up brownies and layer them with ice cream, whipped cream, and chocolate sauce.
- As a Brownie Milkshake – Blend with milk and ice cream for a decadent peanut butter chocolate milkshake.
- With a Caramel or Chocolate Drizzle – Add a little extra sweetness with a sauce drizzle before serving.
- Turned into a Brownie Trifle – Layer brownie chunks with whipped cream and peanut butter mousse for a no-bake dessert.
- Cut into Bite-Sized Pieces for a Dessert Platter – Perfect for parties and gatherings.
- As a Brownie Sandwich – Spread peanut butter or Nutella between two brownie squares for an indulgent sandwich.

Peanut Butter Brownies
Ingredients
- 1 box of chocolate peanut butter brownie mix
- 2-4 tbsp peanut butter
- 1 egg
- 2 tbsp water
- 2 tbsp vegetable oil
Instructions
- Preheat your oven to 320F/160C.
- Mix brownie mix with water, egg, and oil. Use an electric mixer or whisk, and blend until smooth - no lumps!
- Line your tin with parchment, and pour in the mixture evenly.
- Drizzle peanut butter over the mixture, using as much or as little as you like.
- Bake for 15-18 minutes, or until an inserted toothpick comes out clean.
- Leave to cool down on a cooling rack, then cut into squares. Enjoy!
If you’ve tried this recipe, I’d love it if you could spare a minute to pop a review in the comments section below. It helps me to create more recipes and ideas that you’ll enjoy making in your own kitchen!