Toast the walnuts in a dry skillet over medium-low heat for 7 minutes, stirring occasionally until fragrant and lightly browned. Set aside to cool.

Prepare the basil by rinsing and measuring out 2 packed cups of leaves.

Mince the garlic clove or use garlic paste.

In a food processor, combine the toasted walnuts, basil, garlic, Parmesan cheese, and salt. Blend until smooth.

While the food processor is running, slowly drizzle in olive oil until the desired consistency is achieved.

Taste the pesto and adjust seasoning with additional salt or lemon juice, if desired.

Store in an airtight container with a thin layer of olive oil on top to prevent browning.