Preheat the oven to 180 degrees Celsius. Line a 20cmx20cm brownie form with parchment paper.
Melt the butter with the chocolate on low heat either on the stovetop or in the microwave and stir. Beat the eggs with the sugar on high until paler in color and thicker in consistency, this takes a few minutes. Pour in cooled-off chocolate mix and stir. Only add the flour and chocolate chips to combine. Spread in prepared pan.
Bake on medium rack for about 35-40 minutes. An inserted toothpick should still show some crumbs, otherwise you baked it for too long. If there is a lot of batter and it feels very gooey, bake for a few more minutes.
Let come to room temperature, then chill in the fridge. It will be easier to slice. Use, if possible a large bread knife. Brownie slices freeze beautifully.
