Preheat oven to 350°F (177°C). Line an 8 x 8 inch baking pan with parchment paper.

Add eggs to a stand mixer with wire whisk attachment. Beat at highest speed for 8 minutes or until eggs turn thick and pale yellow and should be at least triple in volume. When you lift the beater, the mixture that drips off should be able to stay on top of your egg batter for several seconds before sinking back in. See photo in post for reference. This can be done with a hand mixer but it may take more time.

While your eggs are beating, melt your chocolate. Add chocolate to a large microwave-safe bowl and heat in 30 second intervals, stirring in between with a spatula, until chocolate is completely melted and smooth. You do need to be careful to not overcook your chocolate. If your chocolate is close to being fully melted but needs a little more heat, heat for only 15 seconds instead of 30 seconds. You can also melt the chocolate on the stove using the double boiler method.

Fold your egg mixture into the chocolate in 3 batches. First, add in ⅓ of the egg mixture to the chocolate. Use your spatula to gently fold in the egg mixture. Make sure to scoop the chocolate from the bottom of the bowl so that all the chocolate gets incorporated. Fold until no egg streaks remain. Repeat with second third of egg mixture and then final third of egg mixture. It's okay if you have some small chunks of chocolate in your batter. Finally, gently stir in the lemon juice until just incorporated.

Pour batter into prepared pan. Bake for about 25 minutes or until surface is browned and toothpick inserted comes out clean. Let brownies cool completely to set. Wait until brownies are cooled and set before slicing into squares with a sharp knife. If desired, dust with powdered erythritol before serving.