Lightly toast walnuts in a dry pan for 2-3 minutes before blending to unlock deeper, more complex flavors and reduce any bitterness that can overpower the basil.

Briefly blanch fresh basil leaves in boiling water for 30 seconds, then ice bath and pat completely dry to preserve their vibrant green color and prevent oxidation and browning.

Use a food processor with short pulses rather than continuous blending to maintain texture and prevent heat buildup that can cook the basil and turn the pesto bitter or dark.

Fold in the grated Parmesan cheese by hand after blending, never in the processor, to avoid it becoming paste-like and to preserve its sharp, granular texture in the final pesto.

Finish with a squeeze of fresh lemon juice and taste before adding salt, as Parmesan is already salty—this brightens flavors and prevents an over-salted final product.