Gather all your ingredients.

Heat sugar, corn syrup, and water in a 2-quart saucepan over low heat; stir continuously until sugar is dissolved and mixture comes to a boil. Continue to cook, without stirring, until the mixture reaches 250 degrees F (120 degrees C) or until a small amount of syrup dropped into cold water forms a rigid ball.

Beat egg whites in a 1 1/2-quart glass, metal, or ceramic bowl until stiff peaks form.

Continue to beat while slowly pouring hot syrup in a thin stream into egg whites.

Add vanilla; beat until mixture holds its shape and begins to lose its gloss. Fold in walnuts.