Prepare coffee with shredded orange peel and water in a drip coffee maker or percolator according to manufacturer's directions. Pour coffee into a heatproof pitcher; stir in sugar and milk. Chill at least 3 hours or until serving time.
To serve, fill 6 glasses with ice cubes; pour coffee mixture over ice. Garnish with orange peel strips and grated chocolate, if desired. Makes 6 (6-ounce) servings.