Best Brownie Recipe

These are my favorite brownies:

Ingredients: 
     1 cup butter
     1 1/2 cup flour
     1 cup cocoa powder
     1/2 tsp salt
     1/2 tsp baking powder
     1 cup sugar
     1 Tbsp vanilla extract
     4 eggs
     6 oz chocolate, chopped OR 1 cup semi-sweet chocolate chips

Oven 350°F (175°C)
Instructions:  
     1.  Melt butter on stovetop or in microwave.  Lightly grease 9x13 pan.
     2. While the butter is melting, whisk flour and cocoa together with salt and baking soda.  Set aside.
     3.  Combine melted butter, sugar, and vanilla together.
     4.  Beat the eggs into the butter mixture one at a time, mixing well after each, until thoroughly blended.  
     5.  Gradually stir the flour mixture into the butter mixture.  
     6.  Toss the chocolate in a light dusting of flour and stir them into the batter with a spoon or spatula. (The flour will keep the chocolate pieces suspended in the brownies so you have nice bites of pure chocolate.)
     7.  Pour batter into prepared pan.  Spread the batter in the pan, slightly mounding on sides so it will all bake evenly.  
     8.  Bake for 25-30 minutes or until toothpick inserted comes out clean.  
     9.  Enjoy!

Recipe adapted from http://www.instructables.com/id/Brownie-Recipe/