Prepare the garlic scapes by trimming off the very tops and the bottom root ends. Coarsely chop the scapes.

If your pine nuts are not already toasted, spread them on a dry skillet over medium heat. Toast for 3-5 minutes, stirring frequently, until fragrant and lightly golden. Let cool slightly.

Combine the chopped garlic scapes, basil leaves, toasted pine nuts, lemon juice, salt, and pepper in the bowl of a food processor. Pulse several times until the ingredients are finely chopped but still have some texture.

With the food processor running on low speed, slowly stream in the olive oil until the pesto emulsifies and thickens to your desired consistency. You may not need all the oil.

Add the grated Parmesan cheese during the last few pulses. Stop the machine and scrape down the sides if necessary. Taste the pesto and adjust salt and pepper as needed.

Use immediately, or transfer to an airtight container. Top with a thin layer of olive oil to prevent browning if storing for more than a day. Pesto keeps well in the refrigerator for up to one week.