All ingredients ready? Let's begin!
Preheat the oven to 350F. Prepare a small (8 inch) square pan by lining it with parchment paper and spraying with non-stick spray.
Melt the butter in the microwave and set aside to cool slightly.
In a medium mixing bowl, add the flour, cocoa powder, baking powder, and salt. Whisk together until combined.
In a different, large bowl, beat the egg whites until bubbles form and it becomes frothy. This should take about 5 minutes.
Keep whisking the egg whites while you add sugar, and vanilla. Beat until fluffy and no lumps remain.
Add the dry ingredients to the wet ingredients and mix gently. Try to avoid overmixing; you don’t want any clumps but you also don’t want to overdo it.
Take some cake batter, add to the melted butter. Mix then add the mixture to the cake batter, using folding technique.
Add the chocolate chips and gently fold them into the batter.
Pour the brownie batter into the previously prepared pan.
Put brownies in the oven and bake for 20-25 minutes.
Remove from heat and allow to cool. Turn the pan upside down onto a plate and use the parchment paper sticking over the edges to pull the brownie down if it still sticks.
Cut and serve.