Step 1

Transfer one-third of beans to small bowl. Add remaining beans to food processor along with ½ cup dill, almonds, oil, Pecorino, and salt. Process until combined, about 1 minute, scraping down sides of bowl halfway through processing (pesto will be quite thick and not completely smooth). Transfer pesto to large bowl.

Step 2

Bring 4 quarts water to boil in large pot. Add pasta and 1 tablespoon salt and cook, stirring often, until al dente. Reserve 2 cups cooking water, then drain pasta.

Step 3

Add lemon zest and 1½ cups cooking water to pesto and whisk until combined. Add pasta and reserved beans and toss until pasta is coated in creamy, lightly thickened sauce, 1 to 2 minutes, adjusting consistency with remaining cooking water as needed. Sprinkle with remaining 1½ teaspoons dill and season with salt to taste. Serve immediately.