Bring stout to a boil in a medium saucepan over medium-high heat. Cook until the stout reduces to 1/3 cup (about 15 minutes). Watch the pot during the first couple of minutes to make sure it doesn’t boil over, and adjust heat as needed. Set aside.

Preheat an oven to 350°F. Lightly butter a 9" x 13" baking pan, line with parchment, then lightly butter and flour the parchment. Tap out excess flour. Leave some parchment overhang (see photo above), so you can easily pull the brownies out of the pan.

Add flour, baking soda and fine grain sea salt to a medium bowl, whisking to combine. Set aside.

Bring a large pot filled with 2 inches of water to a simmer. Set a heatproof bowl on top of the pot, but make sure the bottom of the bowl is not touching the simmering water. Add butter and chocolate to the bowl, stirring until melted and combined. Turn off the heat, but keep the bowl on the pot. Whisk white sugar and light brown sugar into the chocolate mixture. Remove the bowl from the pot and whisk in the eggs 1 at a time. Switch to a spatula, then stir in vanilla and reduced stout. Gently fold flour mixture into the chocolate mixture until just incorporated. Then fold in chocolate chips. Do not overmix here. Pour brownie batter into the prepared baking dish. Arrange pretzels in even rows on top of the batter.

Cook for 25 - 30 minutes, or until a toothpick inserted into the center of the brownies comes out with just a few moist crumbs. You may want to test in a few spots, because hitting a chocolate chip with the toothpick will make the brownies seem wetter than they actually are. Transfer the baking pan to a cooling rack, and let cool.

Using the parchment overhang, lift the brownies from the pan, and cut into squares or rectangles, leaving the pretzels on top in tact.