Halibut, Chard and Potato Casserole

1 -1 1/2 lb halibut fillet 2 tablespoons butter (melted) 1 tablespoon canola oil or 1 tablespoon olive oil 2 cups o'brien frozen potatoes (diced) 1 (9 ounce)[...]

2 tablespoons butter 1 large fennel bulb , trimmed, halved and thinly sliced cross-wise 1/2 cup sliced shallot 2 tablespoons all-purpose flour 1 1/2 cups[...]

2 tablespoons extra virgin olive oil 1 medium onion , chopped 2 garlic cloves , minced 1 (14 ounce) can chopped tomatoes , with juice kosher salt & freshly[...]