In a large skillet, toast the pecans over medium high heat for a few minutes.

Line 2 large baking sheets with parchment paper and spray with nonstick cooking spray.

Arrange the toasted pecans in groups of 3, leaving about an inch of space between each group. Set aside.

In a medium saucepan, melt the butter over medium-high heat.

Stir in the brown sugar, corn syrup, and sweetened condensed milk. Cook and stir continuously until it reaches 235-240F on a candy thermometer.

Remove from heat and stir in the vanilla.

Drizzle about 1/2 tablespoon of caramel over each cluster, set aside.

Fill a pot about 1/4 of the way with water, and fit with a bowl that won't touch the bottom of the pot to create a double boiler.

Heat the pot over medium heat.

After letting it heat up for a few minutes, stir the chocolate chips until they are fully melted and smooth.

Stir in the shortening and spoon about 1/2 tablespoon on top of each cluster.

Once the chocolate has cooled, serve immediately or store in an airtight container with parchment paper between each layer of clusters.