Place oven rack in lower third of oven and preheat oven to 325.

Prepare an 8 inch pan with foil or parchment and then spray with cooking spray and set aside.

In a bowl placed over a double boiler with water barely simmering, add sugar, butter and cocoa powder, and salt.

Mix until the butter is melted and mixture is combined.

Remove bowl from heat and let cool for 5 minutes.

Add the vanilla and mix, then eggs one at a time and stir vigorously after each until the mixture is smooth.

Add the flour and mix until incorporated, 40-50 strokes.

Pour batter into prepared pan and smooth the top.

Bake for 20-30 minutes. Mine took 30 minutes, but do test for done-ness starting at 20 minutes, test with a toothpick so that it comes out almost clean.

Cool completely and then cut.