Cut tips from 6 asparagus spears. Prepare a small bowl of ice water and set aside.
Bring a small pot of salted water to a boil. Add asparagus tips and cook, uncovered, for 2 minutes. Transfer to the prepared ice bath to cool. Drain asparagus tips and set aside.
Cut remaining asparagus spears into ½" pieces.
Melt butter in a large pot. Add onion and cook, stirring occasionally, until tender, about 5 minutes.
Add asparagus pieces and parsley and cook, stirring occasionally, for 5 minutes.
Add chicken broth, stir and bring to a boil. Reduce heat to medium-low, cover and simmer until vegetables are very tender, about 15 minutes.