Prepare a baking sheet with a sheet of parchment paper and set aside.
Melt butter and sugar in a non-stick pan over medium heat. Stir with a wooden spoon.
Add the walnuts and the salt and stir to coat the walnuts. Cook another 3 minutes or so, stirring until walnuts are evenly coated and sugar is fully melted.
Remove skillet from stove and pour on to the parchment paper.
Spread the nuts in one layer with the wooden spoon and separate as much as you can. As nuts cool and the coating gets stiffer take the wooden spoon to break apart any clumps or clusters.
Nuts can be refrigerated in an airtight container up to 3 weeks or frozen up to 2 months.