Prep your surface: Line a baking sheet or large cutting board with parchment paper. Keep a spatula nearby.

Warm the walnuts: In a large nonstick skillet over medium heat, add the walnuts and toast for 2–3 minutes, stirring often. You should smell a light nuttiness. Don’t let them darken too much.

Make the coating: Add butter, allulose (or erythritol), water, cinnamon, and salt to the skillet. Stir as the butter melts and the sweetener begins to dissolve, 1–2 minutes.

Optional thickener: Sprinkle in xanthan gum while stirring to avoid clumps. This helps the coating grip the nuts without getting gritty.

Coat the walnuts: Keep stirring as the mixture bubbles gently. In 2–4 minutes, it will thicken and cling to the nuts. Lower the heat if it browns too fast.

Finish with vanilla: Turn off the heat and stir in the vanilla. Mix quickly to distribute evenly.

Spread to cool: Immediately transfer the walnuts to the parchment. Use the spatula to separate clumps so they don’t harden into one mass. If you like, sprinkle a tiny pinch of flaky salt on top.

Let them set: Cool completely, 15–25 minutes. The coating will firm up as it cools.

Break apart and store: Once set, break any large clusters into snackable pieces.