Combine basil, spinach, garlic, parmesan cheese, pepitas, olive oil, salt, pepper, and lemon juice in a food processor or high powered blender and process until smooth. Adding more olive oil if needed. Set aside.
Meanwhile bring a large pot of water to a boil. Generously salt when it becomes a rapid boil, about 2 Tbsp to season the pasta.
Add in the asparagus the last two minutes of boiling time to blanche lightly.
Reserve about 2 cups of pasta water before draining the pasta and asparagus.
Add pasta and asparagus back into the pot and add in pesto and 1 cup of the pasta water at this time.
Stir to combine adding more pasta water if needed for consistency.
Top with extra parmesan cheese and serve immediately.