Directions

1. Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch baking dish.
2. In a medium saucepan over medium heat, melt butter. Stir in the unsweetened chocolate squares and stir until completely melted and smooth. Remove from heat and set aside to cool.
3. In a large bowl, beat eggs until light and fluffy, gradually adding brown sugar and white sugar. Continue to beat for about 3 minutes. Stir in the melted chocolate mixture, vanilla, orange zest and Grand Marinier. Slowly add flour, mixing on low speed, then fold in the chocolate chips and nuts by hand. Spread the batter evenly into the prepared pan.
4. Bake for 45 minutes in the preheated oven, or until sides are slightly dry and the top feels firm to the touch. Allow brownies to cool before cutting into squares. These can be stored covered at room temperature.