Prepare Your Workspace: Line a baking sheet with parchment paper and set it aside.

Melt the Toffee Base: In a medium non-stick skillet over medium heat, combine granulated sugar, butter, and water. Stir until the butter melts and sugar dissolves (3-4 minutes).

Coat the Walnuts: Add walnut halves to the skillet and stir continuously for 5-7 minutes until they absorb the flavors and the mixture thickens.

Enhance the Flavor: Remove from heat, stir in vanilla extract and salt which will create a beautifully flavored candied walnut mixture.

Spread the Candied Walnuts: Transfer walnuts to the baking sheet in a single layer. Allow them to cool for 15-20 minutes until they harden.

Cool and Store: Store cooled walnuts in an airtight container at room temperature for up to two weeks.