Whisk wet mixture into dry mixture until just combined, do not overmix. Stir in chocolate chips or chunks and the walnuts.
The bitters really bring out the flavours in this recipe. As will all recipes, I use bitters as the 'herbs' of baking. They add depth, an added intensity or layer of flavour. Obviously, if you can't find bitters in your neighbourhood, this recipe will work just fine without them. But I truly encourage you to add them to your repertoire and pantry! I was inspired by a recipe found on the Serious Eats website. I decided to amp up the opportunity for coffee flavour, hence there are two places you will find coffee added in my recipe. I also added the walnuts, as well as the topping- for looks and crunch!!
Adapted from Serious Eats