Preheat the oven to 350. Line the bottom of the pan with parchment paper allowing a bit of a lip on the sides. Spray with cooking spray.
Microwave chocolate and butter in a large bowl until melted and smooth, stirring every 30 seconds - 1 minute until everything is melted.
Whisk in granulated sugar and brown sugar.
Next add eggs one at a time until they are each incorporated. Now whisk in the flour, vanilla, and pinch of salt.
Pour into the prepared pan and bake for 40-45 minutes. Things may take longer so just use a toothpick to check. Mine cooked for about 45-50. Since they're a bit gooey inside and I didn't want them to be dry the toothpick was moist but not runny.
Allow these to cool then cut into squares.
Notes
Delicious warm with ice cream! If you don't like cinnamon you can opt to remove it.