Preheat the oven to 425 degrees.
For the pesto, finely chop the garlic, 1 cup baby spinach, walnuts, parmesan, 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. With the motor running, drizzle 1/4 cup olive oil through the feeder tube processing until smooth and combined.
On a sheet pan, toss the asparagus with 1 tablespoon olive oil, 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. Spread the asparagus into a single layer and roast until crisp-tender and bright green, about 7-8 minutes.
Bring a large pot of salted water to a boil, cook the orzo until al dente following the recommended cook time on the package. Save 2 tablespoons of the pasta cooking water. Then drain the orzo.
Stir the pesto with the orzo in a large bowl. Add 1-2 tablespoons of the reserved cooking water, so the pesto coats the pasta.
Fold in the roasted asparagus, 1 cup spinach and chives. Serve topped with additional grated parmesan and chopped walnuts.