Step 1: Preheat the Oven - Start by preheating your oven to 350°F (175°C) while you prepare the brownie mixture.
Step 2: Prepare the Baking Dish - Line your 8x8 inch baking dish with parchment paper, allowing some overhang for easy removal later.
Step 3: Mash the Bananas - In a mixing bowl, mash the ripe bananas using a fork or a whisk. Aim for a smooth consistency, with minimal lumps.
Step 4: Mix in Nutella - Add the warmed hazelnut chocolate spread to the mashed bananas. Stir until the mixture is well combined, and you can’t see any banana lumps.
Step 5: Incorporate Cocoa Powder - Sift in the unsweetened Dutch cocoa powder to avoid clumps. Mix it well into the banana and Nutella mixture until you have a thick batter.
Step 6: Add Fleur de Sel - If using, sprinkle a pinch of Fleur de Sel into the batter and give it one last mix.
Step 7: Bake - Pour the batter into the prepared baking dish and spread it evenly. Bake for about 20-25 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
Step 8: Cool and Slice - Let the brownies cool in the pan for a few minutes before lifting them out using the parchment paper. Slice into squares and enjoy your 3-Ingredient Nutella Brownies!