Margarine tends to make drier brownies while butter produces more moist brownies.  The best ratio is 1/2 stick margarine and 1 1/2 sticks butter.

Melt butter, then sugar, in a sauce pan (pot) big enough to hold all the ingredients on low heat.  If you use chocolate baking squares instead of cocoa powder, melt them with the butter before you put in the sugar.  Mix in the rest of the ingredients into the sauce pan with a wood spoon.

Pour into a 13×9 glass pan and bake 25-30 minutes at 350 °F.