Thaw halibut steaks, if frozen, and cut into 3/4-inch cubes. Discard skin and bones. In a large saucepan cook bacon until crisp. Remove bacon, reserving 1 tablespoon drippings, if desired. Drain bacon on paper towels; crumble bacon and set aside.
In the same saucepan combine reserved bacon drippings (if desired), potatoes, leeks or onion, clam juice, chicken broth, dill, salt, and pepper. Bring to boiling. Reduce heat and simmer, covered, about 15 minutes or until potatoes are tender. With the back of a fork, mash potatoes slightly against the side of the pan.
Combine half-and-half, milk, and flour until smooth; add to potato mixture. Cook and stir just until mixture comes to boiling; add halibut. Reduce heat and simmer, uncovered, for 3 to 4 minutes or until fish flakes easily with a fork.
Stir in spinach. Cook 1 to 2 minutes more or just until spinach is wilted. Sprinkle each serving with crumbled bacon. Makes 4 servings.