Preheat the oven to 350 degrees F. Bake the prepared pie crust for 8-10 minutes and allow to cool completely.

Melt butter and low carb sugar substitute in a large saucepan over medium-low heat. Cook for 6-8 minutes, stirring frequently, until the mixture turns golden brown.

Slowly add 1 ½ cups heavy whipping cream and bring to a simmer for 15-20 minutes, stirring occasionally, until the mixture has thickened and resembles the color of caramel.

Remove the pan from heat and stir in vanilla extract and liquid stevia. Set aside to cool slightly. Meanwhile, in a separate small bowl, bloom the beef gelatin powder in the remaining 1/4 cup cold heavy whipping cream for 5 minutes.

In a clean bowl, gently whisk the large egg. Slowly drizzle ¼ cup of the cooled caramel sauce into the egg, constantly whisking to temper the egg. Gradually whisk in the remaining caramel sauce, then whisk in the bloomed gelatin mixture until fully combined.

Layer the bottom of the cooled pie crust with the chopped raw pecans. Pour the prepared filling mixture over top of the pecans and crust, ensuring all pecans are covered evenly.

Cover the crust edges with aluminum foil or a pie guard to prevent burning. Bake for 45-55 minutes until the filling is set and lightly golden.

Allow the pie to cool for at least 20 minutes at room temperature prior to serving. For best results, store on the counter for up to three days or in the refrigerator for up to ten days.