Preheat oven to 325 degrees F (165 degrees C). Arrange trout fillets in a large baking dish.
Melt butter in a large skillet over medium heat; cook and stir green onion, parsley, and garlic until fragrant, 1 to 2 minutes. Stir in mushrooms and continue to cook until just softened, 1 to 2 minutes more.
Add white wine, lemon juice, salt, and cayenne pepper.
Remove from heat and gently stir in artichoke hearts; pour mixture over trout.
Bake in preheated oven until fish flakes easily with a fork, about 20 minutes.
Remove baking dish from oven and scatter tomatoes over fish.
Set oven rack about 6 inches from the heat source and preheat the oven's broiler.
Return baking dish to oven and broil until fish is browned, 1 to 2 minutes more.