01 - Line a baking sheet with parchment paper and set aside for dropping the pralines later.
02 - In a large, heavy-bottomed saucepan, combine granulated sugar, brown sugar, and heavy cream. Stir to blend thoroughly.
03 - Place the pan over medium heat and stir constantly until the sugars dissolve completely and the mixture starts to bubble.
04 - Add the butter to the bubbling mixture and stir until fully melted and incorporated.
05 - Attach a candy thermometer to the pan. Continue cooking, stirring frequently, until the mixture reaches 238°F (soft-ball stage), approximately 10-15 minutes.
06 - Remove from heat. Add vanilla extract, salt, and pecan halves. Stir vigorously for 2-3 minutes until the mixture thickens and becomes creamy but remains pourable.
07 - Quickly drop spoonfuls of the mixture onto the prepared baking sheet, spacing them about 2 inches apart to prevent spreading.
08 - Let the pralines cool completely at room temperature until set, approximately 20-30 minutes.
09 - Store pralines in an airtight container at room temperature for up to 1 week.