01 - Line a baking sheet with parchment paper and set aside.
02 - In a heavy-bottomed saucepan over medium heat, combine the granulated sugar, brown sugar, heavy cream, butter, and salt. Stir constantly until the butter melts and the mixture comes to a boil.
03 - Attach a candy thermometer to the side of the pan. Continue cooking, stirring frequently, until the mixture reaches 238°F (soft-ball stage), about 8–10 minutes.
04 - Remove from heat and stir in the vanilla extract and pecan halves until evenly distributed.
05 - Continue stirring vigorously for about 2–3 minutes, until the mixture thickens and becomes creamy but is still pourable.
06 - Quickly drop spoonfuls of the mixture onto the prepared baking sheet, spacing them apart to prevent sticking.
07 - Let pralines cool at room temperature until set, about 20 minutes.