Add all the ingredients, except the oil, to a food processor and pulse until the ingredients are combined. (There should still be tiny pieces of pumpkin seeds, herbs and cheese throughout). Stop and scrape down the sides with a spatula, if necessary.
With the food processor running on low, slowly stream in the oil so it emulsifies with the mixture. Again, stop and scrape down the sides, if necessary.
Store pesto in an airtight container in the fridge for 5 days or in the freezer for up to 6 months.
Notes
For extra flavor, buy roasted pumpkin seeds (unsalted) or roast your own.
Slowly stream the oil into the pesto mixture in the food processor so it emulsifies properly.
Pesto will firm up in the fridge so just let it sit at room temperature for 10-15 minutes before using.
If you want your pesto thinner, just add a little more oil or water.
If you like it thicker, use less oil or add more pumpkin seeds.