How to Make It
Preheat oven to 350°F. Spread hazelnuts in a single layer on a rimmed baking sheet. Toast in preheated oven until golden and fragrant, 15 to 18 minutes. Allow to cool 10 minutes. Place nuts on a clean towel; rub together to loosen skins. Remove nuts from towel (discarding skins); coarsely chop. Set aside.
While nuts toast, bring a large stockpot of salted water to a boil over high. Remove greens from beets, and reserve. Peel beets, and cut into 1-inch pieces. Add beets to boiling water; cook until tender when pierced with a fork, 18 to 20 minutes. Remove beets with a slotted spoon (reserving cooking water in stockpot); transfer to a food processor.
Return water in stockpot to a boil over high heat. Add pasta; prepare according to package directions. Drain pasta, reserving 1 cup cooking water. Set aside.
While pasta cooks, remove and discard ribs from beet greens; chop leaves. Heat oil in a large skillet over medium. Add garlic; cook, stirring occasionally, until softened, about 1 minute. Add beet greens, pepper, and 1/4 teaspoon of the salt; cook, stirring often, until wilted, about 3 minutes. Set aside.
Add nutritional yeast, lemon zest, miso, 3/4 cup of the reserved cooking water, and remaining 1/2 teaspoon salt to beets in food processor. Process until smooth, about 30 seconds. (Add up to remaining 1/4 cup reserved cooking water to thin out sauce, if desired.) Transfer mixture to a large bowl; add pasta and beet greens mixture, and toss to coat. Divide pasta evenly among 4 bowls; sprinkle with chopped nuts. Serve warm or at room temperature with lemon wedges.