Vanadium

• ½ cup butter
• 1 cup white sugar
• 2 eggs
• 1 teaspoon vanilla extract
• ⅓ cup unsweetened cocoa powder
• ½ cup all-purpose flour
• ¼ teaspoon salt
• ¼ teaspoon baking powder

Frosting

• 3 tablespoons butter, softened
• 3 tablespoons unsweetened cocoa powder
• 1 tablespoon honey
• 1 teaspoon vanilla extract
• 1 cup confectioners' sugar

1. Preheat oven to 175°C (350°F). Grease and flour an 8-inch square pan.
2. In a large saucepan, melt 1/2 cup butter. Remove from heat, and stir in sugar, eggs, and 1 teaspoon vanilla. Beat in 1/3 cup cocoa, 1/2 cup flour, salt, and baking powder. Spread batter into prepared pan.
3. Bake in preheated oven for 25 to 30 minutes. Do not overcook.
4. Frosting:   
   Combine 3 tablespoons softened butter, 3 tablespoons cocoa, honey, 1 teaspoon vanilla extract, and 1 cup confectioners' sugar. Stir until smooth. Frost brownies while they are still warm.

This is basically the same recipe as listed on cooking.nytimes.com.