Sausage Fennel Stuffing

1/2 stick ( 1/4 cup) unsalted butter

2 medium-large onion s, chopped fine

1 1/2 pounds fennel bulbs (sometimes called anise, about 2 medium), stalks trimmed flush with bulbs and bulbs chopped fine (about 4 1/2 cups)

2 teaspoons fennel seeds, chopped fine

1/4 cup Pernod or other anise -flavored aperitif

2 teaspoons dried thyme , crumbled

2 teaspoons dried tarragon , crumbled

5 cupscorn bread for stuffing or packaged corn bread stuffing