Spread the pecans evenly on a baking sheet and bake them in a 350-degree F oven (175 degrees C) for approximately 7-10 minutes (they're ready when you start to smell them). Set aside to cool.
Meanwhile, melt the butter over medium-low heat in a 3-quart, heavy-bottom saucepan.
Add the corn syrup, brown sugar, and salt and cook, occasionally stirring, until all the sugar has dissolved.
Gradually add in the sweetened condensed milk and cook and stir over medium-high heat until the mixture comes to a boil.
Continue boiling the mixture, stirring frequently. Be patient as you'll be boiling and stirring for approximately 15-18 minutes.
Continue boiling and stirring until the mixture reaches 248-degrees F (firm ball stage) on an instant read candy thermometer.
Turn off the heat and stir in the pecans and vanilla extract until well combined.
Carefully drop the caramel and nut mixture, by tablespoon measurements, onto parchment-lined baking sheets, spacing them about 2" apart. If desired, sprinkle each caramel lightly with a touch of kosher salt. Refrigerate until firm.
Meanwhile, melt the chocolate chips and the shortening together in a microwave-safe bowl on half power at 30-second intervals, stirring at each interval until the chocolate is smooth and melted.
Dollop each turtle with approximately 2 teaspoons of melted chocolate (or you can drizzle chocolate over the top using a piping bag or fork) and return the turtles back to the refrigerator to firm up before serving.
Video
Notes
Store the completed candy in an airtight container in the refrigerator for up to 2 weeks.May be frozen. Store in an airtight freezer container for up to 2 months.