1/3 cup (5 Tablespoons; 71g) unsalted butter, softened to room temperature
1/2 cup (100g) packed light brown sugar
2 large eggs, at room temperatur
2 teaspoons pure vanilla extract
1 and 1/4 cups (370g) Nutella, divided
1/2 teaspoon salt
3/4 cup (94g) all-purpose flour (spooned & leveled)
optional: 3/4 cup (135g) semi-sweet chocolate chips; a sprinkle of sea salt
Preheat oven to 350°F (177°C). Line the bottom and sides of an 8-inch square baking pan or 9-inch square baking pan with aluminum foil or parchment, leaving an overhang on all sides to easily lift the brownies out of the pan when cool. (If using a 9-inch pan, the bake time will be a few minutes less.) Set aside.
With a handheld or stand mixer fitted with a paddle attachment, beat the butter on high speed in a large bowl until smooth and creamy, about 1 minute. Add the brown sugar and beat on high speed for 1-2 minutes until creamed. Scrape down the sides and up the bottom of the bowl as needed. With the mixer running on low speed, add the eggs and vanilla extract. Beat on medium-high speed until combined, then beat in 1 cup Nutella and salt. Mix until smooth and fluffy. Scrape down the sides and up the bottom of the bowl as needed. With the mixer running on low speed, add the flour, mixing just until combined. Do not overmix. If using chocolate chips, gently fold them in.
Pour the batter into prepared baking pan. Drop teaspoonfuls of the remaining 1/4 cup Nutella on top. Using a knife, swirl the Nutella into the batter. Top with a sprinkle of sea salt.
Bake the brownies for 32-36 minutes. Keep your eye on them and test with a toothpick to determine doneness. If the toothpick comes out with only a couple moist crumbs, the brownies are done. The brownies may take a few minutes longer; all ovens vary. Mine took 36 minutes.
Allow the brownies to cool completely in the pan set on a wire rack. Once cool, lift the foil out of the pan using the overhang on the sides and cut into squares. You can top each with more sea salt if desired. Store in an airtight container at room temperature or in the refrigerator for 3-4 days. They won’t last that long!