01 - Line two baking sheets with parchment paper or silicone mats to prevent sticking.
02 - In a heavy-bottomed saucepan over medium heat, combine granulated sugar, brown sugar, butter, heavy cream, milk, and salt. Stir constantly until butter melts and sugars dissolve completely.
03 - Attach a candy thermometer to the pan. Continue cooking, stirring occasionally, until mixture reaches 236°F (soft ball stage), about 8-10 minutes.
04 - Remove from heat immediately. Stir in vanilla extract and toasted pecans. Beat briskly with a wooden spoon for 2-3 minutes until mixture thickens to a creamy, pourable consistency.
05 - Working quickly, drop heaping tablespoons onto prepared baking sheets, spacing 2 inches apart to allow for spreading.
06 - Let pralines cool completely at room temperature for at least 20 minutes until firm and set.