Preheat oven to 325F. Melt butter in a double boiler or a small saucepan over low heat. Pour butter into a mixing bowl and then using same pan, melt chocolate on low heat.
Add sugar to the melted butter and mix well. Add eggs one at a time, beating by hand between each addition. Add vanilla and melted chocolate.
Sift flour with baking powder and salt. Add flour mixture to chocolate mixture. Stir in nuts (optional).
Pour batter into a greased 13 x 9 pan (or if you like thick, fudgier brownies, use an 8x8 pan).
Bake for 35-45 minutes, or until a toothpick inserted in the center comes out clean.
Recipe by In Good Taste at http://ingoodtaste.kitchen/cake-nor-candy/