Preheat oven to 400° F. Combine brown sugar and beer in a small bowl, whisking well to form a thin syrup. Set aside.
Line a rimmed baking sheet with aluminum foil. Place a wire cooling rack on top. Place the pieces of bacon on top of the rack, overlapping if necessary. Place in oven and cook for 10 minutes.
Remove from oven and brush one side of the bacon with the beer syrup. Flip the bacon and coat the other side with the syrup. Return to oven and cook for another 10 minutes. Remove from oven and repeat this process another time or two until the bacon is crispy and browned and you’ve used all the glaze.
Cool on wire rack for 20 minutes, then remove to a plate and cool for at least 1 hour before serving.