Preheat oven to 350 degrees. Line cookie sheet with parchment paper.
In a large bowl, using a hand or stand mixer, beat butter, brown sugar, and granulated sugar until light and creamy.
1 cup unsalted butter, 1 cup light brown sugar, ½ cup granulated sugar
Add in eggs and vanilla; mix until combined. Set aside.
2 large eggs, 1 teaspoon vanilla extract
In a large bowl, whisk flour, salt, baking soda, and coffee granules. Add flour mixture into the batter and mix until well combined.
2 2/3 cups all-purpose flour, ½ teaspoon kosher salt, 1 teaspoon baking soda, 2 ½ tablespoons instant coffee granules
Using a medium cookie scoop (2 tablespoons in volume), scoop dough into balls and drop 2 inches apart on prepared cookie sheet.
Bake for 8-10 minutes, or until tops are no longer wet. Cool on baking sheet for 2 minutes, move onto rack to finish cooling.
In a medium bowl, whisk cocoa powder and powdered sugar until well combined. Add in vanilla and milk; continue whisking until any lumps are mostly gone. NOTE: If glaze is too runny, add a little more powdered sugar. If the glaze is too thick, add a little more liquid. ¼ cup unsweetened cocoa powder, 1 cups powdered sugar, 1 teaspoons vanilla extract, 3 tablespoons milk
Pour glaze into Ziploc bag, snip the corner off and drizzle glaze over cookies.
Allow cookies to sit for 30 minutes. When glaze is set, cookies can be stacked or stored.