• Preheat oven to 350°F and line an 8-inch square baking pan with parchment paper or aluminum foil and set aside.
• In a large mixing bowl with a hand mixer or a stand mixer fitted with a whisk attachment, beat together the chocolate-hazelnut spread and eggs until completely combined, about 1 minute. Do not mix by hand.
• To accurately measure the flour, spoon it into the measuring cup so that it's heaping, then gently shake the measuring cup from side to side to remove some of the excess flour but DO NOT level off. Add the flour and salt to the hazelnut-egg mixture, and mix just until combined, scraping the sides of the bowl as needed.
• Spread the brownie batter into the prepared baking pan.
• Bake for 18 to 20 minutes or until a toothpick inserted comes out clean.

For fudge-like brownies:

• Prepare the recipe as directed through Step 3. Stir in the chocolate chips before transferring the brownie batter to the prepared baking pan, and bake as directed.

For nutty brownies:

• Prepare the recipe as directed through Step 4. Sprinkle the top of the brownie batter with the chopped hazelnuts. You can do this with both the cake or fudge brownies. Bake as directed.