Prepare Your Workspace: Line two large baking sheets with parchment paper or silicone mats. Set aside.
Combine Ingredients: In a heavy-bottomed saucepan, combine the light brown sugar, granulated sugar, heavy cream, butter, and salt.
Cook the Mixture: Place the saucepan over medium heat. Stir constantly with a wooden spoon until the sugar has completely dissolved and the butter has melted.
Bring to Temperature: Once the mixture begins to boil, attach a candy thermometer to the side of the pan, making sure the tip is submerged but not touching the bottom. Continue to cook, stirring occasionally, until the mixture reaches the soft-ball stage, between 236-240°F (113-115°C).
Remove from Heat: Immediately remove the saucepan from the heat.
Add Flavor and Nuts: Carefully stir in the vanilla extract and the pecan halves until they are evenly distributed.
Beat the Candy: Let the mixture cool in the pan for 1-2 minutes. Then, begin beating the mixture vigorously with the wooden spoon. Continue to beat for 2-3 minutes, until the candy begins to lose its glossy sheen and starts to thicken and look slightly opaque. This step is crucial for the creamy texture.
Drop the Pralines: Working quickly, use two tablespoons to drop spoonfuls of the mixture (about 2 tablespoons each) onto the prepared baking sheets, leaving space between each one.
Cool and Set: Let the pralines sit undisturbed at room temperature for at least 30 minutes, or until they are completely firm and set.