On top of a double boiler, melt the butter, sugar, cocoa and salt. Melt, stirring occasionally. Let the mixture cool a bit.
Add the eggs one at a time. Add in the vanilla.
When everything is nice and combined add the flour.
Line an 8×8 inch baking pan with parchment or tin foil. Let the parchment hang over the side of the pan so that you can get the brownies out easily when they are cool. Pour the batter into the prepared pan.
Bake at 325 degrees for 20 to 25 minutes.
Remove the brownies from the oven. Let them stand for a few minutes to cool, then pull the brownies out of the pan using the parchment paper.