Preheat oven to 350°F. Line a baking sheet with parchment. Place a large piece of parchment on a work surface.

Distribute walnuts in a single layer on prepared baking sheet and bake, stirring occasionally, until toasted, 10 minutes. Use a chef's knife to chop finely.

Place honey in a large saucepan over medium heat. Using a silicone spatula, stir until the honey just begins to boil, about 5 minutes.

Add sugar and stir in. Continue to cook and stir until the mixture boils and starts to foam up. Drop a small amount into a glass of cold water. If it balls up and hardens, the mixture is ready; otherwise, continue cooking and testing.

Remove from heat and stir in chopped walnuts.

Scrape mixture onto parchment and spread with spatula. Place another piece of parchment on top, and use a rolling pin to roll to a thickness of about 1/4 inch.

Peel off top piece of parchment and try to straighten edges using a dampened bench knife.

Let cool for 20 minutes, then cut into 1-inch by 2-inch diamonds. Layer on waxed paper in an airtight tin and store in refrigerator.