Preheat the oven to 350 °F and place the walnuts in a single layer on a large cookie sheet. Roast for 6-9 minutes until very lightly browned with a toasty smell. Remove the sheet pan from the oven and let them cool.
To the base of a food processor, add the toasted walnuts along with the garlic cloves. Pulse several times until coarsely chopped.
Add the basil, spinach, lemon juice, salt and pepper. Run on medium for 10-20 seconds until chopped.
While the food processor is running, slowly drizzle in the olive oil. Continue processing until the mixture is smooth and well combined, stopping and scraping down the sides as needed.
Add the shredded parmesan to the pesto and pulse a few more times to incorporate. Taste and add salt and pepper as needed.
Use as desired.
Video
Notes
To Store: Place leftover pesto in an airtight container and store it in the refrigerator for up to 4 days.To Freeze: For longer storage, you can freeze the pine nut free pesto in a freezer safe container for up to 3 months.I like to freeze it in ice cube trays. Then once frozen, transfer the pesto cubes to a ziptop bag and store them in the freezer. Then you can grab just the right amount to defrost in the fridge when you need it.