Preparation Boil broth with garlic, thyme, zest, and 1/4 teaspoon pepper in a large heavy skillet until reduced to about 1 cup, about 6 minutes. Discard thyme sprigs and zest. Meanwhile, cook tortellini in a pasta pot of boiling salted water (1 1/2 tablespoons salt for 4 quarts water) according to package directions. Drain. Stir cornstarch into cream, then whisk into broth. Bring to a simmer, whisking, then continue to simmer 1 minute. Add asparagus and simmer until crisp-tender, about 2 minutes. Stir in cheese and tortellini and cook, gently stirring, until heated through.
Preparation Boil broth with garlic, thyme, zest, and 1/4 teaspoon pepper in a large heavy skillet until reduced to about 1 cup, about 6 minutes. Discard thyme sprigs and zest. Meanwhile, cook tortellini in a pasta pot of boiling salted water (1 1/2 tablespoons salt for 4 quarts water) according to package directions. Drain. Stir cornstarch into cream, then whisk into broth. Bring to a simmer, whisking, then continue to simmer 1 minute. Add asparagus and simmer until crisp-tender, about 2 minutes. Stir in cheese and tortellini and cook, gently stirring, until heated through.