Preheat oven to 160ºC .
Line a 33 cm x 23 cm glass pan with a double layer of tin foil. Extend the foil ends a couple of inches over the shorter side of the pan. Grease the tin foil with butter.
In a large microwave proof bowl, place unsweetened chocolate and butter. Nuke until melted, about 3 minutes or so. Mix in sugar, blend well. Allow to cool a bit. Add the three eggs; beat in well. Now add the flour, blending it in well. Add the nuts.
Pour batter into the prepared baking dish. Sprinkle the chocolate chips evenly over the batter.
Bake at 160ºC or 30 minutes or until a toothpick comes out clean. Don't overcook this. Remove from oven. Allow to cool before cutting. Cut into portions which meet with your discretion! Should make quite a few. This is a dense, chewy, fudgey type brownie.