Combine the sugar, corn syrup and water in a medium saucepan. Heat over low heat, stirring frequently, until the sugar is dissolved.
Bring the sugar mixture to a boil over medium heat. Continue to boil without stirring until the sugar reaches hard ball stage, or 260 degrees F, on a candy thermometer. You may need to adjust the heat a little to reach the correct temperature. Remove the saucepan from the heat.
While the sugar is boiling, beat the egg whites at medium speed until stiff peaks form.
Switch to the paddle attachment on your mixer. With the mixer running, add the sugar mixture in a slow and steady stream.
Once all the sugar has been added, continue to beat the egg whites until the whites have lost their glossy sheen and the mixture holds a shape, about 10-15 minutes.
Add the vanilla and chopped pecans. Mix on low speed until the pecans are evenly incorporated throughout the divinity.
Spoon heaping tablespoons of divinity candy onto waxed or parchment paper.
Top each piece of candy with a pecan half.
Allow the divinity to dry at room temperature for a minimum of two hours, up to 24 hours.
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Notes
Store homemade divinity candy in an airtight container or freezer bag in a cool dry place. Consume within two weeks. Divinity candy can also be frozen for up to two months.