12 tablespoons unsalted butter, room temperature
1 tsp instant coffee
1 teaspoon cinnamon
1/2 cup chopped walnuts
2 tablespoons coffee liqueur (or vanilla extract)
Egg wash (1 egg beaten lightly)
1 cup powdered sugar
2 tablespoons milk
Preheat oven to 350 degrees and line a baking sheet with parchment paper.
In a large bowl, blend the butter and egg together. Slowly add the dry mix, instant coffee, 1/2 teaspoon of cinnamon, coffee liqueur and walnuts and mix until a dough forms.
On the parchment paper, shape the dough into a log, about 10" long. Gently flatten the top so you have a long rectangle shape. Brush the top with the egg wash.
Bake for 30 minutes until the dough becomes golden brown across the top and feels firm and dry to the touch. Remove from oven and cool 10 minutes. Once the baked dough is cool enough to handle, cut it crosswise into 1/2" thick slices.
Place slices on the baking sheet, cut sides down, and bake 10 more minutes. Turn biscotti over and cook another 10 on the other side. Transfer to a wire rack and cool completely.
Make glaze by whisking the powdered sugar with 1/2 teaspoon of cinnamon and milk until a thick glaze forms. Drizzle on biscotti.