Line 1-2 baking sheets with parchment paper. Set aside.
Add a candy thermometer to a medium-heavy saucepan taking care to not let it rest against the side or bottom of the pan.
Heat the sugar, corn syrup, and water over medium heat until it reaches the hard-ball stage (250- 260 °F).
While the syrup is cooking, beat egg whites until stiff peaks form.
Once the sugar reaches the proper temperature, remove it from the heat and very slowly AND VERY CAREFULLY pour it into the whipped egg white, whipping on high speed constantly.
Add the vanilla and continue beating on high until candy holds its shape. (about 10- 15 minutes)
Spray a cookie scoop or 2 spoons with cooking spray or cooking oil. Then drop scoops of candy onto the prepared baking sheets.
Immediately add whole pecans on top or another garnish, if using.
Allow the divinity to dry and harden for several hours or overnight at room temperature.
Store in an airtight container for up to two weeks.