Preheat your oven to 350°F (175°C). Grease an 8x8 inch baking pan or line it with parchment paper for easy removal.
In a medium saucepan, melt the butter or coconut oil over low heat. Once melted, remove from heat and let it cool slightly.
In a large mixing bowl, combine the melted butter or coconut oil with the light brown sugar and natural sweetener. Whisk until well combined. Add the eggs, one at a time, followed by the vanilla extract. Mix until smooth.
Pour the warmed Nutella into the wet mixture and stir until fully incorporated, creating a luscious chocolate base.
In a separate bowl, sift together the flour, cocoa powder, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Gently fold in the raspberries, blueberries, and chocolate chips into the brownie batter, being careful not to overmix.
Pour the brownie batter into the prepared baking pan and spread it evenly. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for about 10-15 minutes. Once cooled, lift them out using the parchment paper (if used) and slice them into squares.
