Add the pecan halves to a saucepan and heat over medium heat. Toast the pecans until fragrant, about 3-5 minutes, stirring often to keep them from burning.
Add in the sugar, water, and salt and stir until the sugar and salt are fully dissolved.
Bring the mixture to a gentle simmer, and simmer for 10 minutes.
Remove the saucepan from the heat and pour the syrup through a strainer into a mason jar or heat-proof container, catching the pecans inside the strainer. Don't throw away the pecans, set them aside for later.
Stir in the vanilla/maple/butter extract, if using.
Let the syrup cool completely before adding a lid, and store in the fridge for up to 3 weeks.
Spread the strained pecans onto a parchment paper lined baking sheet in a single layer, and bake at 375 degrees Fahrenheit for 10-12 minutes, or until slightly browned (keep an eye on them so they don't burn).
Let the candied pecans cool fully before storing in an air-tight container at room-temperature for up to 7 days.