01 -
Preheat the oven to 350°F. Line an 8x8-inch metal baking pan with foil or parchment, leaving an overhang, and spray with nonstick cooking spray.
02 -
In a large microwave-safe bowl, combine the chocolate chips, butter, and unsweetened chocolate. Heat in the microwave for 1 minute, then stir. Continue heating in 30-second bursts, stirring between each burst, until melted and smooth. Let cool slightly, then stir in the Nutella.
03 -
In a large mixing bowl, use an electric mixer to beat the eggs and sugar on medium-high speed until light and thick, about 3 minutes. Beat in the vanilla extract.
04 -
Stir the cooled chocolate mixture into the egg mixture using a rubber spatula. Gently fold in the flour, cocoa powder, and sea salt until just combined.
05 -
Pour the batter into the prepared baking pan, smoothing it out evenly. Bake for 35 to 40 minutes, or until a toothpick inserted into the center comes out with moist crumbs still attached. Avoid overbaking.
06 -
Let the brownies cool to room temperature in the pan. Serve at room temperature, warmed, or chilled as preferred.