Heat oven to 375°F (if using dark or nonstick cookie sheet, heat oven to 350°F). In 2-quart saucepan, melt butter over medium heat. Stir in brown sugar, coffee crystals and corn syrup. Heat to boiling over medium-high heat, stirring constantly, until sugar is dissolved. Remove from heat. Stir in flour, cocoa, hazelnuts and vanilla until blended.