Beat egg whites until soft peaks begin to form. Add sugar, salt, and vanilla; beat until stiff peaks form and turn glossy. Fold in nuts and coat well with the egg white mixture.
Melt butter in a 9x13 baking pan by placing pan in the oven. Evenly spread coated nuts over melted butter in pan.
Bake for 30 minutes, stirring and turning nuts about every 8 minutes, or until butter no longer remains in pan. Place hot nuts on foil and allow to cool. May be stored in an airtight container for several weeks.