Preheat oven to 350° F. Grease a 9 x 9 inch baking pan
Put butter and chocolate chips in a microwave-safe bowl and heat for 30 seconds, stir and microwave for another 30 seconds. Repeat if necessary to melt the chocolate chips.
In a large mixing bowl combine melted chocolate with brown sugar and eggs. Stir in Dr. Pepper and vanilla extract.
Add flour, cocoa powder, instant coffee, and salt. Stir just until combined.
Pour into prepared baking pan.
Bake for 35 to 45 minutes, let stand for 5 minutes in the pan and transfer to a cooling rack.