1 stick of butter (completely melted)
½ cup flour
1 cup sugar
2 eggs
¼ teaspoon salt
1 teaspoon vanilla
1/3 cup cocoa
1 Tablespoon peanut butter

Preheat oven to 375°F. 

Melt stick of butter in microwave. 

Pour flour and sugar in with butter.  Stir. 

Add eggs, cocoa, vanilla, and salt, stirring after each one. 

Grease 9-inch baking pan. 

Pour in brownie mixture. 

Just before putting in the oven, melt 1 Tablespoon of peanut butter in the microwave.

With a spoon, drizzle peanut butter on top of mix.

Bake for approximately 30 minutes.