Cook beer in a medium saucepan over medium heat for 20-25 minutes, or until reduced to 1/2 cup of liquid. Cool for 15 minutes.
Meanwhile, preheat oven to 350°F. Line the bottom of a 8x8 inch square baking pan with parchment paper, leaving a bit of overhang on 2 sides.
Microwave 6 oz. of chopped chocolate and butter in a large, microwave-safe bow until melted and smooth, stirring at 30-second intervals. You will need to microwave the chocolate and butter for a total of about 1 1/2 - 2 minutes.
Once the chocolate and butter are melted, whisk in the sugars until combined. Add the eggs in, one at a time, whisking until just blended in.
Once cooled, whisk in the reduced beer along with the vanilla and 1/2 tsp of sea salt.
Whisk in the flour and cocoa until just combined. Do not over mix. Pour the mixture into the prepared baking pan and sprinkle with the remaining 2 oz. of chocolate and 1/2 tsp. of salt.
Bake for 50 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs clinging to it. Do not overbake.
Cool completley on a wire rack in the pan. Once cooled, remove brownies from the pan using the parchment paper overhang. Cut into squares and enjoy!