Roasting walnuts releases aromatic compounds that impart a deep, smoky quality to their flavor. Several confectionery applications, such as cakes and pastries, and savory preparations, such as walnut and basil pesto, require toasting the walnuts before use. Roast shelled walnuts prior to using them in recipes that call for chopped walnuts, as small pieces tend to burn quickly.
Preheat the oven to 350 degrees Fahrenheit. Coat the walnuts with a thin layer of olive oil.
Place the walnuts on a sheet pan in a single layer without overcrowding. Season the walnuts with kosher salt if desired.
Roast the walnuts for eight to 10 minutes, or until the desired color is achieved.
Store roasted walnuts in an airtight container for up to two weeks.
Heat a cast-iron skillet to medium-high. Cast-iron distributes and retains heat better than stainless steel or aluminum, and contributes to uniform roasting.
Roast the walnuts for three to five minutes, or until desired color is reached. Stir the walnuts for even cooking.
Store roasted walnuts up to two weeks in an airtight container.