In a pan over a medium-low flame, toast the almonds & walnuts until fragrant & golden brown & set aside to cool. Add a mortar & pestle add in whole almonds and pound until they are in large chunks. Remove and repeat with the walnuts and set aside.
In a food processor add in all the basil and run until all the basil is chopped into small pieces (you can do this by hand and add it in a well. I just find it easier to do it all in the processor). Then add in the lemon juice & zest, salt, pepper, & garlic and blend until garlic isn't in chunks anymore. Slowly stream in the olive oil and blend until completely combined. Now add in crushed nuts and pulse until combined, but not completely smooth (make sure that the nuts still have lots of texture to them).
Store in an airtight container in the fridge for a week or in the freezer for up to 3 months.
• I don't add parmesan to my pesto if I'm going to be freezing it. I've found that the pesto goes rancid very quickly when the cheese was added in. Instead, I add it in when I'm going to use the pesto. You can add it in if you want to skip this step when making the pesto.
• You can use any nuts you have at home for this pesto. My favorite version is with pistachios!