Combine the beer and brown sugar in a saucepan. Heat over medium-high heat and bring to a slight boil. Reduce the heat to low and simmer for 20 minutes or until the liquid reduces by half. Take off the heat and allow to cool completely.
Preheat an oven to 350°F. In a small bowl, combine the all-purpose flour, rolled oats, baking powder, salt, and cardamom. Set aside. In another bowl, place the butter and mix until smooth.
Add the sugar to the butter and mix until smooth. Add the beer and sugar mixture.
Add the egg to the mixture and mix. Slowly mix in the flour mixture until it just comes together.
Add the chocolate chips and fold them in.
Take about a tablespoon of the dough at a time, place on a baking sheet and press down slightly into a cookie shape. Place in the oven to bake for 13-16 minutes.
