Add basil, walnuts and garlic to the bowl of a food processor and pulse until everything is finely minced.
Add Parmesan cheese to the food processor and pulse again until the cheese is combined.
With the food processor running, stream in olive oil until pesto reaches a beautiful creamy consistency.
Season with salt and pepper to taste.
Notes
Parmesan: Make sure to grate your own fresh parmesan for pesto. The pre-grated options will not have the same great flavor or texture.
Substitutions: Pistachios, almonds and cashews are all great substitutes for walnuts in this recipe.
Leftovers: Store basil pesto in an airtight container in the refrigerator with a thin layer of olive oil on top to prevent browning. It will keep for up to 1 week.
Freezer: Spoon pesto into ice cube trays or small containers, freeze, then transfer to a freezer-safe bag. It’ll keep for up to 3 months. Thaw in the fridge before using.