In a saucepan over medium-high heat, bring the beer to a boil and cook until reduced to 1/4 cup (25-30 minutes). Remove from heat.

While reduction cools. Line an 8"x8" baking pan with parchment paper leaving extras to use as "handles".

Affix a candy thermometer to the rim of a large pot and heat the condensed milk, semi-sweet and dark chocolate chips over medium heat until the mixture is heated to 225ºF – 235ºF. Everything should be completely melted and mixture should be smooth.

Remove from heat and mix in the vanilla and beer reduction.

While still warm, place mini pretzels on top of the fudge to make a grid. You should use about 36 mini pretzels (8×8)

Refrigerate fudge for at least 2 hours.