Preheat your oven to 425°F and bring a big pot of water to a boil.
Trim off the woody bottoms of the asparagus. Toss the asparagus with oil, salt and pepper.
Spread the asparagus out on a rimmed baking sheet in one even layer. Roast for 15 to 20 minutes until tender and starting to brown.
Meanwhile, cook the ziti (or pasta of choice) according to package directions in well salted water.
While the pasta is cooking and the asparagus is roasting, make the sauce.
In a small skillet, heat 2 teaspoons of oil (or 2 tablespoons of vegetable broth) over medium-high heat. Sauté the diced onion for 4 to 5 minutes until soft and translucent. Add the minced garlic and sauté another 1 to 2 minutes.
Combine the beans, onion/garlic mixture, vegetable broth, lemon juice, and salt in a high speed blender and purée until smooth. Add a little more broth (or some of the pasta water) to thin if needed.
To serve, combine the ziti and sauce and serve the asparagus either on the side or mixed in with the noodles.
Garnish with extra lemon zest, parsley, and an extra squeeze of fresh lemon, if desired.