Preheat oven to 400°.
Heat 1 T oil in a large ovenproof skillet over medium-high heat. Add onions and cook, stirring often, until just starting to soften, 5 to 7 minutes.
Add wine, increase heat to high and cook, stirring often, until the wine is slightly reduced, 2 to 4 minutes.
Place cod on the onions and sprinkle with thyme, salt and pepper. Cover the pan tightly with foil; transfer to the oven and bake for 12 minutes.
Toss bread with the remaining 1 tablespoon oil, paprika and garlic powder in a medium bowl. Spread the bread mixture over the fish and top with cheese. Bake, uncovered, until the fish is opaque in the center, about 10 minutes more.
Message: This is a great way to get kids introduced to fish meals. It tastes like a mild fish gratin and isn't "fishy" at all.