Heat the light cream in a heavy 2-quart saucepan to lukewarm (110ºF.) Reserve 1/2 c cream and set it aside. Add the sugar, corn syrup and salt to the remaining 1/2 cup of cream in the saucepan. Cook over medium heat, stirring constantly, until the mixture boils. Slow stir in the reserved cream. Cook, stirring constantly, for 5 minutes. Stir in the butter, 1 teaspoon at a time, stirring constantly. Cook over low heat, stirring constantly, until the mixture reaches the soft ball stage, (234ºF.) on the candy  thermometer. Remove from the heat and stir in the vanilla. Arrange the pecans on a waxed-paper lined baking sheet. Drop the mixture by teaspoonfuls onto the pecans. As the clusters cool, remove with a metal spatula to another waxed-paper lined baking sheet. Push the remaining pecans together and repeat until all of the candy mixture is used. If the mixture becomes too thick, heat over low heat. Melt the chocolate chips over hot water and stir until smooth. Spread on the top of each pecan cluster. Let stand until the chocolate is set and store the candies in a cool place. Makes about 4 dozen.