Directions

1. Preheat oven to 350 degrees F (175 degrees C).
2. In a medium bowl, cream together 1/3 cup butter and 1/2 cup brown sugar. Stir in 1 cup of flour until well blended. Press the dough into the bottom of a 9x13 inch baking pan.
3. Bake for 10 minutes in the preheated oven; remove and set aside. In a medium bowl, mix eggs and vanilla. Combine 1 cup brown sugar, 2 tablespoons flour, baking powder and salt so there are no lumps. Stir the sugar mixture into the eggs. Stir in the chocolate chips. Spread over the pre-baked crust.
4. Bake for 15 to 20 minutes in the preheated oven, until golden brown. Cool and drizzle with chocolate glaze.
5. To make the glaze: In a small saucepan over medium heat, mix together the cocoa, 4 teaspoons butter, and boiling water. Cook over low heat, stirring occasionally, until thick and smooth. Remove from heat and stir in the confectioners' sugar. Drizzle over cooled bars before cutting into squares.