Place the pecans on a baking sheet and bake in a preheated 350°F (175°C) oven for 8-10 minutes or until fragrant. Allow them to cool.
Prepare your baking sheet for the pecan pralines by lining it with greased parchment paper or a silicone mat.
Combine the granulated sugar, brown sugar, cream, unsalted butter, and salt in a medium-sized saucepan.
Place the saucepan over medium heat and bring the mixture to a gentle boil, stirring constantly.
Once the mixture reaches a boil, insert a candy thermometer into it. Cook the mixture until it reaches a temperature of 235°F/112℃ (soft ball stage). It will foam and bubble slightly. Stir occasionally to ensure even heating and to prevent burning.
Remove the saucepan from the heat. Let it sit for a few minutes to cool slightly and thicken, reaching about 200°F (93℃).
Add the pecan halves, chopped pecans, and vanilla extract to the mixture. Stir them in with a wooden spoon to coat, and then do not stir again. Let the temperature come down to 150°F (65℃), then stir again for about a minute.
Using a spoon or cookie scoop, drop spoonfuls of the pecan praline mixture onto a parchment-lined baking sheet. Allow the pralines to cool and set completely at room temperature, which will take about 30 minutes to an hour.
Once the pecan pralines have completely set, remove them from the baking sheet and store them in an airtight container at room temperature.