Preheat oven to 350°F. Line an 8 x 8 inch baking pan with parchment paper.
In the bowl of a stand mixer (you can also do this with a hand mixer), add eggs. Using the wire whisk attachment, beat eggs until frothy. Increase mixing speed to highest setting and continue to beat eggs for about 8 minutes. You want to beat the eggs until they change color (they will become a very pale eggshell yellow), the egg mixture becomes more than triple in volume and the egg mixture becomes very thick. To check if your mixture is ready, lift up your beater and watch the egg mixture that drizzles down from your beater back into the bowl. It should sit on the surface of your mixture for several seconds and not immediately sink in. See photo in post for reference.
While your eggs are beating (if you are using a hand mixer you can do this after), melt your chocolate. You can do this in the microwave or on the stove. If using microwave, melt at 30 second intervals (this should take around 2 minutes total), stirring in between, until chocolate is completely melted and smooth.
Let chocolate cool slightly so it's no longer too hot to touch. You don't want the chocolate to cool completely because then it won't be melted anymore. Add in 1/3 of the egg mixture. Fold in the egg mixture using a spatula until egg is completely incorporated. Repeat with another 1/3 and then remaining 1/3. Towards the end, your chocolate may start getting a little stiff. That is okay. Break up any chocolate clumps using your spatula.
Pour batter into prepared pan. Bake for about 25-30 minutes or until a toothpick inserted comes out clean. The surface of the brownies should also be firm. Let brownies cool before cutting and serving.
Notes
10 oz is weighted ounces. It is a little more than 1 1/2 cups of chocolate chips but you should measure out the weight for best results. If you don't have a scale, most chocolate chip packages are sold in 10 oz packages so just use a 10 oz bag.
You can also make this using chocolate bars. You would need to roughly chop the chocolate down to the size of chocolate chips.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.