1. Toast pepitas in a dry skillet over medium heat, tossing often, until seeds turn golden and start to pop, about 3 minutes. Transfer to a bowl to cool.
2. With food processor running, drop in garlic to chop. Pulse in parsley, lemon zest and juice, red pepper and 1/2 tsp. salt. Pulse in cheese and pepitas. Scrape down sides of bowl. With machine running, drizzle in oil. Season with salt and pepper.
Make it ahead
TO FREEZE: Portion into ice cube trays. Add a little olive oil on top to help keep the pesto green.
TO SERVE: Defrost frozen pesto overnight in the fridge, then bring to room temperature, 20 to 30 minutes, stirring occasionally.