Line a baking sheet with a silicone mat or a piece of parchment paper lightly spritzed with baking spray.
Separate the egg whites and transfer to the clean bowl of your stand mixer fitted with a whisk attachment.
Add sugar, water, salt, and corn syrup to a medium pot then stir together and place over medium heat. Once the mixture comes to a boil stop stirring and use your candy thermometer to keep track of the heat. You need to remove the pot from heat immediately when you’ve reached 255F. When your sugar mixture nears 230F turn the mixer to high and beat the egg whites to stiff peaks.
As soon as your sugar mixture reaches 255F remove from heat and Slowly drizzle into the egg whites while the mixer runs on high. This will take a few minutes as you will be drizzling a thin stream into the egg whites to be patient.
Run the mixer for 4-5 minutes or until you start seeing the gloss fade. You can spoon a test batch onto the baking sheet and see if it holds its shape.
Immediately mix in the vanilla and pecans then turn mixer off and use two spoons to portion out 1-2 tablespoon-sized pieces onto a parchment or silicone lined baking sheet. Allow to set before storing in an airtight container.
Notes
Make sure to have your silicone mat or parchment-lined baking tray ready before starting. You have to work quickly to avoid the candy setting in the bowl.
Make sure you have a reliable candy thermometer, it's essential that the sugar reaches the correct temperature or it might not set properly.
You can tell the divinity mixture is ready when the gloss starts to fade but you can also test to see if it is ready but dolloping a small amount onto parchment paper. If it holds its shape it's ready but if it sinks into a puddle it not ready yet.
Wait until the sugar has reached 230F to whip the egg whites you want the sugar and egg white to be ready at the same time.
You'll need to use a stand mixer to make this, motors in hand mixers tend to be much weaker and since this is a very thick and sticky consistency hand mixers will probably struggle.