in a saucepot over a low flame, melt the sugar and butter together. Once melted, add the cocoa powder and espresso powder.
preheat the oven to 325 degrees F. also butter a 9x9 brownie/cake pan. (I use a round one because I don't have a square).
once the ingredients above are melted together, turn the heat off, and wait for it to cool a little. Once sufficiently cool, add the vanilla extract, then the eggs, one by one, beating them in so its fully incorporated.
add flour, again whisking the flour in slowly so that it is fully incorporated.
pour the batter into the buttered cake pan. To your liking, sprinkle sea salt on top, so that it is evenly distributed.
Place in oven, in the middle rack. Bake for approximately 25 minutes.