Combine instant coffee, sugar,and salt in a saucepan. Add milk, cream, and corn syrup. Stirring constantly, bring to a boil. Continue cooking, stirring occasionally, to soft ball stage, or about 234° on a candy thermometer. Remove from heat. Cool to lukewarm, or 110°; beat until mixture loses its gloss. Add nuts and chocolate chips. Stir slightly for marbled effect. Turn into a lightly buttered 8-inch square pan. Garnish with pecan halves, if desired.