Chocolate pecan brownies

This is my adaptation of a recipe I found in a Morrisons magazine, the one that comes free with your shopping at the checkout. Very, very nice..............

12oz good butter (don't skimp and use anything else, makes all the difference),  melted
4 oz good quality  Fair Trade cocoa
scant 1 lb granulated sugar
4 medium sized free range eggs
8 oz self raising flour
4 oz pecan nuts, chopped

When butter is melted, add rest of ingredients and beat well; turn into buttered and floured tin, bake in a hot oven until well risen and firm to touch. Turn out on to cooling rack, then cut into small squares. Keeps well in an airtight tin (if you can).
Can be iced with eg fudgey icing, but it's rich enough as is, without this.
Endlessly adaptable.