Line baking sheets with waxed paper; lightly coat with nonstick cooking spray and set aside. Butter the sides of a heavy saucepan with 1 teaspoon butter. Cube remaining butter; place in pan. Add corn syrup, brown sugar and salt. Cook and stir until sugar is melted.

Gradually stir in milk. Cook and stir over medium heat until mixture comes to a boil. Cook and stir until a candy thermometer reads 248° (firm-ball stage), about 16 minutes. Remove from the heat; stir in vanilla. Gently stir in pecans. Drop by rounded teaspoonfuls onto prepared baking sheets. Refrigerate until firm, about 12 minutes.

In a microwave-safe bowl, melt the chips and shortening; stir until smooth. Drizzle over clusters. Chill until firm. Store in the refrigerator. Yield: about 6 dozen.

Note: We recommend that you test your candy thermometer before each use by bringing water to a boil; the thermometer should read 212°. Adjust your recipe temperature up or down based on your test.