Chewy Peanut Butter Banana Brownies Recipe

I’m not entirely sure what sparked the idea for these peanut butter–banana brownies. A few weeks ago I had some overripe bananas on the counter and intended to make chocolate chip banana bread. Instead, I wondered whether mashed banana could replace part of the butter in a brownie. From there it was a short leap to the classic flavor trio—chocolate, banana, and peanut butter—and I pictured a fudgy brownie with a peanut butter swirl.

Once I had that vision, I needed a reliable brownie base. I considered several tried-and-true recipes, but ultimately I kept thinking of the tahini-halva brownies from Sweet, by Yotam Ottolenghi and Helen Goh. That recipe’s rich, fudgy texture and tahini swirl felt like the perfect starting point for a peanut-swirled banana brownie. The original uses a generous amount of butter, which made me comfortable replacing roughly half of it with mashed banana without sacrificing richness.

My first batch proved the idea was solid: chocolate, banana, and peanut butter harmonized beautifully and yielded an intensely fudgy brownie where nobody missed the extra butter. Aesthetically, though, my first swirl experiment wasn’t as pleasing as I’d hoped. I had mixed a small amount of peanut butter with banana and a splash of cream to make it more swirlable, but that caused the peanut butter to seize and thicken instead. I also wanted a bolder peanut butter presence.

For round two I researched chocolate–peanut butter brownies to see how other recipes handled the peanut element. Many recipes turn peanut butter into a sweet filling by mixing it with powdered sugar, butter, or egg. I didn’t want that; I wanted the peanut butter to perform like tahini in the Ottolenghi version—a smooth, slightly savory foil to the sweet, chocolaty batter. The solution was simple: gently heat plain smooth peanut butter until it loosens, and increase the amount so the peanut flavor is more present. That adjustment made all the difference.

The finished brownies are richly chocolatey, with a subtle banana depth and a distinct peanut butter swirl that brightens and balances the dessert. Their texture stays very fudgy even when fully cooled, with a gooey center that brownie lovers will appreciate. The flavor profile reminded me of another recipe from Sweet—the chocolate banana pecan cookies—so these brownies are, in a way, a mash-up of ideas inspired by that cookbook. I’m perfectly fine with that: the result is delicious.

Peanut Butter-Banana Brownies

A silky chocolate-banana brownie is finished with a peanut butter swirl for a decadent, balanced treat. Loosely adapted from Sweet, by Yotam Ottolenghi and Helen Goh.

Ingredients

• 125 g unsalted butter, cut into chunks
• 200 g semisweet chocolate, chopped
• 60 g unsweetened chocolate, chopped
• 135 g mashed very ripe banana (about 2 small bananas)
• 4 large eggs
• 280 g sugar
• 120 g all-purpose flour
• 30 g Dutch-process cocoa powder
• 1/2 tsp table salt
• 75–90 g smooth peanut butter (see notes)

Instructions

1. Preheat the oven to 400°F (200°C). Line a 9-inch square baking pan with parchment paper.
2. In a heavy saucepan over low heat, melt the butter with the chopped semisweet and unsweetened chocolate, stirring occasionally. When most of the chocolate has melted, remove from heat and stir until fully smooth.
3. Let the chocolate-butter mixture cool until just warm, then stir in the mashed banana.
4. Sift together the flour, cocoa powder, and salt.
5. In a large bowl, use an electric mixer to whisk the eggs with the sugar until pale and creamy, about 3 minutes. Fold in the chocolate-banana mixture with a spatula, taking care not to overmix.
6. Gently fold in the sifted flour, cocoa, and salt until just combined.
7. Scrape the batter into the prepared pan, smoothing the top with a spatula.
8. Warm the peanut butter in the microwave or a small saucepan until it thins to an almost-pourable consistency (about 30 seconds in the microwave at low power). This makes it easy to dollop and swirl.
9. Spoon spoonfuls of the warmed peanut butter over the brownie batter, then drag a skewer or toothpick through the batter to create a marbled pattern.
10. Bake for 23–25 minutes, until the center still has a slight wobble. The brownies will set more as they cool.
11. Cool completely before slicing for the cleanest cuts, though these are excellent warm if you prefer gooey centers.

Notes

I used a creamy supermarket-style peanut butter that’s lightly sweetened and low in salt. You can use a sweeter peanut butter or a natural-style peanut butter if you prefer; natural versions may separate and require stirring, and they can be a little more assertive in flavor.

If you use about 90 g of peanut butter, the brownies become very peanut-forward—delicious if you want a stronger peanut presence. Use closer to 75 g for a subtler swirl.

These brownies are intentionally very fudgy; even when fully cooled, the center will be rich and slightly gooey. Most fans of dense, fudgy brownies will consider that a feature, not a flaw.