Optional chocolate chips or chunks---I never add themthese are already quite sweet for our tastes but you do what you need to do ?
1. Preheat oven to 350 degrees. Grease a 9×9-inch baking pan.2. Microwave butter until melted, stirring as needed to prevent splattering. Add cocoa and coffee or water and stir until smooth.3. In a medium-sized bowl whisk together the eggs and the sugar for 2 minutes. Add the vanilla extract. Add the chocolate mixture into the sugar mixture slowly while stirring to combine.4. Add the flour, baking powder and salt. Add the chopped walnuts, reserve some for the top if desired.5. Pour the batter in the pan, top with nuts if desired. Bake for 21-25 minutes until a toothpick comes out mostly clean. If gooey lava cake style is desired they can be underbaked a few minutes.6. Remove from the oven and allow to fully cool before cutting into bars (or dig in with a spoon!) Enjoy!