Nutella Swirled Banana Blondies

If you're a fan of banana bread, you'll be an even bigger fan of these banana blondies! They're filled with super sweet mashed bananas, rich and nutty brown butter, and silky smooth chocolate hazelnut swirls in every square. These blondies are the perfect quick dessert for birthdays or parties–and the best part is, you can add as much Nutella as you want!

For more blondie recipes, try Brownie Blondies, Gingerbread Blondies, and Gooey Candy Bar Blondies.

Why you'll love these banana blondies

• Pronounced Banana Flavor: There's no mistaking the banana in these blondies! You'll taste sweet banana throughout the entire batch, especially if they're as ripe as possible.
• Moist & Chewy Texture: These blondies are the perfect balance of banana bread and blondies–soft and moist like banana bread, but still dense and chewy like brownies and blondies.
• Rich Notes of Brown Butter: The brown butter gives these blondies a rich, decadent flavor that compliments the super sweet bananas and Nutella.
• Creamy Nutella Swirl: Enjoy a swirl of creamy, chocolatey Nutella with every bite you take–and add as much as you like!

Ingredient Notes

• Nutella: Use your favorite chocolate hazelnut spread to top these blondies. I used Nutella!
• Bananas: Use over-ripe, browning bananas for the sweetest flavor.
• Flour: Use high quality unbleached all-purpose flour best results.
• Sugars: I opted for dark brown sugar in this recipe because the extra molasses content that adds more depth of flavor, but you can use light brown sugar. 
• Butter: Make sure to brown your butter for the best overall flavor.
• Eggs: You'll only need one egg and one egg yolk.
• Vanilla: Add a high quality vanilla extract for optimal flavor.

See recipe card for full information on ingredients and individual quantities.

Step by Step Ingredients

Here are step by step photos and instructions on how to make this Nutella swirled banana blondie recipe! For the full ingredient list and method, see the recipe card at the end of this post.

STEP 1: Mix dry ingredients. In a medium bowl, combine the flour, baking powder, and salt. Set aside.

STEP 2: Brown the butter. Melt the butter over medium heat, stirring with a rubber spatula as it melts. Once the butter turns a dark golden color and the fat solids have darkened and settled at the bottom of the pan, remove from heat and immediately pour into a large bowl, scraping out the fat solids at the bottom. Weigh out the butter to 184g (13 tbsp). 

STEP 3: Whisk. To the brown butter, whisk in the brown sugar and granulated sugar. Then, vigorously whisk in the egg, egg yolk, and vanilla until fully combined.

STEP 4: Mash bananas. On a medium plate, mash the bananas until smooth.

STEP 5: Add bananas. Whisk the mashed bananas into the batter.

STEP 6: Mix in dry ingredients. Add the dry ingredients to the batter and use a rubber spatula to fold until just combined. 

STEP 7: Spread Nutella. Prepare a 9 inch baking pan with parchment paper. Pour the batter into the pan, then dollop the Nutella on top and use a toothpick to swirl it in. 

STEP 8: Bake. Bake the banana blondies for about 30 minutes until evenly golden. Allow them to cool completely in the pan before removing and cutting into 16 squares.

Expert Baking Tips

• Start with 227g (16 tbsp) unsalted butter. Start with a few extra tablespoons of butter, since water evaporates as it browns. Also, keep in mind that European-style butter has less water content, so if you're using American-style butter you might want to start with even more butter.
• Use very ripe bananas. The riper the better! Bananas become sweeter and more flavorful as they ripen, so wait until your bananas are spotty and falling off of their stems to make these blondies. 
• Measure the Nutella with your heart. There's no right or wrong amount of Nutella, so add as much or as little as you'd like! 

All of the recipes on this blog are carefully developed with gram measurements so you can easily recreate them in your own kitchen with success. Volume measurements are extremely inaccurate and leave room for significant errors. Not all measuring cups are made equally, so your one cup of flour will be different from my one cup of flour. By providing precise measurements in grams (aside from minor ingredients, which are given in tsp/tbsp), you can make these recipes accurately and with less cleanup! All you need is this kitchen scale. 

If this still isn't enough to convince you, I have provided volume measurements in the recipe card. If you are interested in understanding the conversions, this is the best conversion chart.

But trust me, once you try baking in grams you'll never turn back!

Happy baking! x