Add egg whites to a large mixing bowl and let sit at room temperature for 20-30 minutes.
Cover two baking sheets with wax paper and fill a small bowl with ice water; set both aside.
Mix corn syrup, sugar, and water together in a saucepan. Bring to a boil, then reduce to medium heat. Continue to cook until the candy is in a soft ball stage (see below), then move onto the next step.
Beat the egg whites on medium-high for 5-6 minutes or until stiff peaks have formed.
Once your candy has reached its hardball stage, reduce your mixer speed to medium-low. Remove the candy from heat and slowly add to the egg whites.
Note: It's important to keep the mixer going from here on out. As tempting as it might be to check your progress, let your divinity mix undisturbed for at least three minutes after adding the candy.
After four to five minutes of mixing, add the vanilla extract. Add cinnamon and nuts if desired. Mix until combined.
Spoon a small dollop of candy onto the wax paper. If it holds its shape and doesn't turn into a candy puddle, it's ready to be transferred from the mixing bowl. If the divinity is still runny, continue mixing, testing for doneness every 30 seconds to 1 minute.
Use a greased spoon to scoop out a hefty tablespoon-size dollop of divinity. Using a second greased spoon, push the candy off the first spoon onto the baking sheet. Your dollops don't have to be perfect! Think of them as beautifully mismatched, fluffy clouds of deliciousness.
Let candy set at room temperature until dry to the touch. Store in an airtight container with wax paper in between layers. The divinity will last for up to 5 days.