Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone mats. Spread the pecan halves in a single layer and toast for 6 to 8 minutes until fragrant. Let them cool completely.

Once cooled, arrange the pecans onto the parchment-lined baking sheets in small clusters of three or four nuts, positioned close together. Ensure you leave adequate space between each cluster for the caramel to spread.

In a heavy-bottomed 3-quart saucepan, combine the unsalted butter, both sugars, and heavy whipping cream. Place over medium heat, stirring constantly until the butter is melted and the sugar has dissolved.

Bring the mixture to a gentle, steady boil. Clip a candy thermometer to the side of the pot and continue boiling, stirring only occasionally, until the caramel reaches the soft-ball stage: 240°F (115°C). This usually takes 10 to 15 minutes.

Immediately remove the saucepan from the heat. Carefully stir in the vanilla extract and the 1/2 teaspoon of fine sea salt. Allow the caramel to cool slightly in the pan for 3 to 5 minutes to thicken slightly before pouring.

Working quickly while the caramel is still warm, use a small spoon (or measuring tablespoon) to dollop the caramel generously over the center of each pecan cluster, binding the nuts together. Be careful not to use too much, or the caramel will pool excessively.

Allow the clusters to cool completely and set the caramel. This can take 30 minutes at room temperature, or 15 minutes if placed in the refrigerator. The caramel must be firm to the touch before dipping.

Melt the chocolate and optional shortening/oil in a microwave-safe bowl (30-second intervals) or over a double boiler until perfectly smooth and glossy.

Dip Method: Carefully dip the bottom of each caramel-pecan cluster into the chocolate, or fully submerge the entire cluster using two forks. Return the finished turtle to clean parchment paper. Drizzle Method: Use a fork or spoon to liberally drizzle the chocolate over the tops of the set caramel clusters.

Optional: Sprinkle a pinch of sea salt on top while the chocolate is still wet. Let the completed clusters rest or chill for 30 minutes until the chocolate shell is completely hardened. Store in an airtight container.