Combine the Guiness and 1/4 c. brown sugar in a saucepan. Cook over medium heat, stirring for about 15-20 minutes until it has reduced and becomes thick.

Put the Guiness syrup aside to cool a bit.

Preheat the oven to 325 F.

Mix the flour, cocoa, baking powder, baking soda and salt together.

In a mixer bowl cream the butter with the white and brown sugar until well mixed.

Add the eggs and vanilla and beat well.

Add the dry ingredients and the Guiness mixture and mix.

Stir in the chocolate chips.

Roll the dough into balls and bake on parchment lined cookie sheets for 12-15 minutes.