Preheat the oven to 350F. Line a baking sheet with parchment paper.
Arrange the walnuts in a single layer on the baking sheet.
Bake for 10 to 15 minutes or until fragrant and starting to brown, stirring every few minutes. Remove and let cool completely. Use as desired or store in an airtight container.
Stovetop Method:
Place the walnuts in a large skillet. Cook over medium heat stirring frequently until browned and fragrant, 8 to 12 minutes.
Remove from the skillet and let cool. Use as desired or store in an airtight container.
Notes
Size matters. You can use walnut halves, walnut pieces, or chopped walnuts, just choose all of one type so they cook evenly. The smaller the pieces, the less time it will take to toast the nuts, so keep an eye on them.
Use your senses. Nuts will change in both color and smell as they toast. Oftentimes, you’ll be able to smell when they’re done as the walnut skins toast and oils heat up. The color will darken, but the intense nutty smell is easier to use as a gauge of when they’re done.
Walnuts should be stored in an airtight container once completely cooled. (Don’t try and store them before they’ve cooled to room temperature— the resulting condensation will make them stale in a heartbeat!) If you plan on storing them long-term, you can refrigerate or freeze them for 2 to 3 months. If you store the toasted walnuts at room temperature, keep them in a dark, cool place and use them within 1 week.