Ingredients
225g butter, chopped
450g dark eating chocolate, shopped
1 1/2 cups (450g) firmly packed brown sugar
5 eggs, beaten lightly
3 teaspoons vanilla essence
1 cup (160g) plain flour
1 cup (200g) dark choc bits
3/4 cup (180g) sour cream.
1 tablespoon cocoa powder for dusting (if desired)

Method
1. Preheat oven to moderately slow (about 160°C). Grease 20cm x 29cm approx. rectangular slice pan; line base and two opposite sides with baking paper.
2. Melt butter and chocolate in medium saucepan; stir over low heat, without boiling, until mixture is smooth. Cool until just warm.
3. Stir in sugar, egg and essence, then sifted four, choc bits and sour cream. Spread mixture into prepared pan.
4. Bake for about 40 minutes.  Cover pan with foil and bake for another 20 to 30 minutes (depending on how sticky you like your brownies).  Stand brownie in pan until it reaches room temperature.
5. Cut into squares, dust with sifted cocoa to serve.