In a separate large mixing bowl, combine (but do not beat!) the eggs, coffee crystals, vanilla, and sugar; stir this mixture into the melted chocolate mixture and allow this to cool to room temperature.
In another bowl, toss the remaining 1/4 cup flour with the remaining 12 oz. of chocolate chips and all of the nuts; gently fold this into the prepared chocolate brownie batter.
Let the brownies cool completely then frost with Miss Sue’s Luscious Chocolate Frosting (recipe below); cut into squares and serve.
In a separate mixing bowl, combine the cocoa powder with the powdered sugar, then add this mixture to the butter mixture, beating until smooth. (Add more liquid or powdered sugar, as desired, to make the frosting the desired consistency you prefer.)
This recipe makes a large batch of frosting and can be refrigerated for later use. Once the frosting has chilled be sure to let it come to room temperature and softened before trying to use it.