Preheat the oven to 350F and coat an 8x8 baking pan with non stick spray. Line the pan with parchment paper.
Place the butter and chocolate chips in a microwave safe bowl. Melt the chocolate chips and butter in the microwave, stirring every 15 seconds to prevent burning.
Once the butter and chocolate chips are melted, stir them well to combine.
Add the sugar and mix well using an electric mixer or a whisk.
Add in the eggs and mix well.
Mix in Nutella and make sure it's fully combined.
Add in the flour and mix well make sure there are no flour pockets in the batter.
Transfer the batter into the baking pan and bake in the oven for 20 to 25 minutes. The edges should be set and the center would be just a bit jiggly.
Let it cool for about 15 minutes before slicing.