Preheat your oven to 300 degrees Fahrenheit and line a large baking sheet with parchment paper. Add the basil, rosemary, sage, thyme, and salt to a small bowl and stir to combine, then set aside.
Add the walnuts to the prepared baking sheet, then pour the olive oil over the nuts and stir until the nuts are all completely coated. Sprinkle with the herb mixture and stir to coat. Spread the nuts into a single layer on the baking sheet.
Place the baking sheet onto the center rack of your preheated oven and bake for 12 - 15 minutes at 300 degrees Fahrenheit, or until they are cooked to your liking.
Remove the nuts from the oven and allow them to cool for at least 10 minutes. They get crunchier once they have cooled completely.
Notes
Storage: I store my nuts in an airtight container in the refrigerator so that they stay fresher longer.