Roast the pumpkin: If using fresh pumpkin, peel, seed, and chop it into cubes. Toss the pumpkin cubes with olive oil, salt, and pepper, then roast them at 400°F (200°C) for about 20-25 minutes until soft and lightly caramelized.

Blend the pesto: In a food processor, combine the roasted pumpkin, basil, pine nuts, Parmesan (if using), garlic, and lemon juice (optional). Blend until the mixture becomes smooth.

Add olive oil: With the processor running, slowly stream in the olive oil until the pesto reaches your desired consistency. Taste and adjust salt, pepper, and lemon juice as needed.

Serve: Toss the pumpkin pesto with pasta, spread it on sandwiches, or drizzle it over roasted vegetables. You can also use it as a dip for bread or crackers!

Enjoy your creamy, nutty, and slightly sweet pumpkin pesto!