- 1 1/2 pounds halibut fillets, cut into 1-inch cubes
- 2 tablespoons (1/4 stick) butter
- 1 large fennel bulb; trimmed, halved, thinly sliced crosswise
- 1/2 cup sliced shallots (about 2 medium)
- 2 tablespoons all-purpose flour
- 1 1/2 cups vegetable broth
- 1 six-ounce package baby spinach
- 3 1/2 cups warm mashed potatoes
Melt butter in heavy large saucepan over medium heat. Add fennel and shallots. Cover; cook until tender, stirring occasionally, about 8 minutes.
Sprinkle with flour, salt, and pepper. Sauté for 2 minutes.
Add broth; bring to boil, stirring often. Add fish and spinach. Cover; simmer over medium heat until fish is almost cooked through, about 4 minutes.
Transfer fish mixture to 11x7x2-inch baking dish. Spoon mashed potatoes over, covering completely. Broil until filling bubbles at edges and potatoes are brown in spots, about 4 minutes.