Position knife blade in food processor bowl. Add cookies and 2 tablespoons espresso granules; process until mixture resembles fine crumbs. Set aside.
Line a 13" x 9" x 2" pan with a large sheet of aluminum foil, allowing foil to extend 1" beyond ends of pan. Butter the foil and set aside.
Combine remaining 2 tablespoons espresso granules, sugar, 1/2 cup butter, and milk in a large saucepan. Cook over low heat until sugar and espresso granules dissolve, stirring occasionally. Bring to a boil over medium heat, stirring constantly. Boil 5 minutes, stirring constantly, until mixture reaches soft ball stage or candy thermometer registers 234°. Remove from heat.
Add candy coating and marshmallow cream, stirring until candy coating melts. Stir in hazelnuts and vanilla. Gently fold in reserved cookie crumb mixture, creating a speckled effect.
Spread mixture into prepared pan. Let cool completely. Carefully lift foil out of pan. Cut fudge into small squares.