On two parchment-lined sheet trays, divide the pecan halves into 30 piles, about 3-4 pecans for each pile. Evenly top with the chopped pecans, and set aside.
Slice the butter and add it to a dutch oven or medium-sized pot along with the brown sugar, granulated sugar, and corn syrup.
Bring to a low boil over medium heat, stirring constantly.
Add the sweetened condensed milk, and mix it in well. Continue to cook, constantly stirring, so it doesn’t burn, until the mixture reaches 240°F.
Take off the heat, and continue to stir until it begins to thicken, 5 minutes. Stir in the vanilla.
Working quickly, drizzle about ½ tablespoon of the caramel over the piles of pecans. Try to drizzle the caramel over all the pecan pieces so they stick together. Repeat with the remaining pecans and caramel.
Let the candy sit for about 30 minutes until the caramel is set. You can also place them in the refrigerator to speed up the process.
In a medium-sized bowl, add the chocolate chips and shortening. Microwave in 15-second intervals, stirring in between until smooth.
Use a 1 teaspoon measuring spoon and dollop the melted chocolate into the center of each turtle, smooth it out slightly. You will use about ½ - ¾ teaspoon of chocolate for each one.
Let the turtles sit out at room temperature for 2-3 hours, or you can pop the trays into the refrigerator for 1 hour to set. Enjoy immediately, or store between layers of parchment paper in an airtight container.