Ramp Pesto Spaghetti

Blanch greens from 4 ounces ramps (about a fistful) in a large pot of boiling salted water until wilted, about 10 seconds. Let cool in ice water; drain and squeeze out liquid. Return pot of water to a boil and cook 12 ounces spaghetti, stirring occasionally, until al dente; drain, reserving 1 cup cooking liquid. Meanwhile, coarsely chop 2 ramp bulbs and stalks (save or pickle the rest) and 1/4 cup toasted walnuts in a food processor. Add ramp greens, 1/3 cup olive oil, and 2 tablespoons grated Pecorino; process to a coarse paste. Season with salt. Toss spaghetti and 1/2 cup cooking liquid with pesto, adding more cooking liquid as needed until pesto coats pasta. Serve topped with more Pecorino and with lemon wedges.