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