Preheat oven to 325°F.
Add the melted butter and brown sugar to the bowl of a stand mixer, beat until well combined, at least 5 minutes.
Add the egg yolk, beating until the mixture resembles frosting, about 6 minutes.
Add the molasses, brown ale and vanilla, beating until well combined.
Stop the mixer, add the flour, spices and baking powder, beating until just combined. Stir in the chocolate chips.
Add a sheet of parchment paper to a baking sheet. Using a cookie scoop, scoop out balls of dough, placing evenly spaced on the baking sheet.
Bake for 12-15 minutes or until edges have started to brown. Remove from oven, pull the parchment off the baking sheet and onto a flat surface to cool.