Step 1: Preheat oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper.
Step 2: In a medium bowl, whisk together Nutella and eggs until smooth and well combined.
Step 3: Gently fold in flour and salt until just incorporated, being careful not to overmix.
Step 4: Stir in chocolate chips if using, then pour batter into prepared pan and spread evenly.
Step 5: Bake for 25-30 minutes until edges are set but center is still slightly soft.
Step 6: Let cool completely in pan before cutting into squares and serving.