Pasta with Sausage and Broccoli Rabe

Place sausage and 1/2 cup water in a large skillet over medium-low heat. Cover and simmer for 10 minutes; drain. Cut sausage into 1/3-inch-thick slices. Heat olive oil in same skillet over medium-high heat. Add sausage and cook until browned, about 6 minutes, turning once. Transfer to a plate, reserving oil. Meanwhile, boil a large pot of salted water. Add broccoli rabe and cook until leaves are wilted, 1 to 2 minutes. Using a slotted spoon, transfer broccoli rabe to a colander and drain. Return water to a boil. Add cavatelli and cook according to package instructions. In same skillet over medium-high heat, add broccoli rabe and garlic. Cook until broccoli rabe is tender, about 4 minutes. Return sausage to skillet and reduce heat to low. Strain cavatelli, reserving 1/2 cup cooking water. Stir cooking water into skillet, scraping up browned bits from bottom. Toss pasta with broccoli rabe mixture and serve immediately.