Amazing Brownie Recipe

A few months ago, I was browsing online for HOURS trying to find a viable, made-from-scratch recipe for chewy brownies. To no avail, I was otherwise unable to strike gold. However, this one recipe that I picked up while on the search proved to be somewhat close to the texture I had yearned for.
Unfortunately, I lost the website and am incapable of crediting the owner of this recipe. But thanks to whoever you are! (Note: I do believe that I skimmed some other recipes from different sites that had almost the same ingredients and processes involved but I don't think I want to worry about that too much.)


INGREDIENTS:
1 cup [225 grams] butter
16 tablespoons [1 cup] cocoa powder
2 cups sugar
4 eggs
1/2 teaspoon salt
1/2 teaspoon baking powder
2 teaspoons vanilla extract
1 cup flour

THE BROWNIE:
1. Pre-heat oven, and floor the bottom and sides of a reasonable-sized baking pan.
2.At a low heat, melt the butter in a saucepan.
3. Sift the cocoa powder into the melted butter and mix well.
4. In a large mixing bowl, beat the sugar and eggs until fluffy.
5. Add the salt, baking powder, and vanilla extract into the large bowl and mix.
6. Mix in the butter and cocoa mixture into the large bowl and mix.
7. Add the flour last and mix thoroughly.
8. Pour in the batter into the baking pan and spread it out evenly.
9. Bake for 25-30 minutes at 350 degrees or until toothpick comes out clean.
10. Enjoy!

NOTES:
-If you do not have butter, you can substitute with margarine. But when I did that, I realized that the taste was much different than what I would have gotten from the butter.
-Once, I forgot to add the flour, but the result was rather enjoyable!
-I am not confident in the number 350 up there. I use a gas oven, so I looked around and threw in the most common temperature available because I couldn't say, "...bake it at a 2-3cm, blue flame and adjust according to whatever conditions your oven might be prone to."